Il presente lavoro è stato parzialmente finanziato dal IGF-progetto &quot;S-Sieve&quot; (490 ZBG / 1), finanziato dal BMWi e BMBF-progetto &quot;Aptasens&quot; (BMBF / DLR 01RB0805A). Un ringraziamento speciale a Tobias J. Günther per il suo prezioso aiuto durante gli studi AFM e di Erik V. Johnstone per aver letto il manoscritto come un madrelingua inglese. Inoltre, l&#39;autore di questo articolo ringrazia Aline Ritter e Sabrina Gurlit (da Istituto di ecologia delle risorse per l&#39;assistenza nelle misurazioni ICP-MS), Manja Vogel, Nancy Unger, Karen E. Viacava e la biotecnologia del gruppo del Helmholtz-Institut Freiberg per Technology Resource.

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In questo lavoro ha studiato il legame di Au alle proteine ​​S-layer è stata studiata utilizzando una combinazione di diversi metodi di analisi. In particolare, il legame di Au è molto interessante non solo per il recupero di Au da acque minerarie o soluzioni di processo, ma anche per la costruzione di materiali, ad esempio, superfici sensoriali. Per gli studi di interazione Au (Au (III) e Au (0) -NPs) con sospensione e ricristallizzata monostrato di SLP1, la proteina doveva essere isolato. Perta...

A causa della crescente uso di oro per diverse applicazioni come l&#39;elettronica, catalizzatori, biosensori o strumenti medici, la domanda di questo metallo prezioso è cresciuta nel tempo degli ultimi anni 6-9. L&#39;oro così come molti altri metalli preziosi e pesanti vengono rilasciati nell&#39;ambiente tramite scarichi industriali in concentrazioni diluite, attraverso attività minerarie, e lo smaltimento dei rifiuti 7,8,10, anche se la maggior contaminazione ambientale da metalli pesanti o preziosi è un processo in corso principalmente causato da attività tecnologiche. Questo porta ad una interferenza significativa di ecosistemi naturali e potrebbe minacciare la salute umana 9. La conoscenza di questi risultati negativi promuove la ricerca di nuove tecniche per rimuovere i metalli da ecosistemi e miglioramenti contaminati nel riciclaggio dei metalli dalle acque di scarico industriali. Metodi fisico-chimici ben affermati come precipitazione o scambio ionico non sono così efficaci, specialmente in altaly diluito soluzioni 7,8,11. Bioassorbimento, sia con la vita o la biomassa morti, è un&#39;alternativa interessante per trattamento delle acque reflue 10,12. L&#39;uso di tali materiali biologici può ridurre il consumo di prodotti chimici tossici. Molti microrganismi sono stati descritti per la costituzione o immobilizzare metalli. Per esempio, le cellule di Lysinibacillus sphaericus (L. sphaericus) JG-A12 hanno dimostrato elevate capacità di legame per i metalli preziosi, per esempio, Pd (II), Pt (II), Au (III), e altri metalli tossici come Pb (II) o U (VI) 4,13, cellule di Bacillus megaterium per Cr (VI) 14, le cellule di Saccharomyces cerevisiae per Pt (II) e Pd (II) 15, e Chlorella volgare Au (III) e U (VI) 16 , 17. Il legame di metalli precedenti, come Au (III), Pd (II), e Pt (II) è stato riportato anche per Desulfovibrio desulfuricans 18 e per L. sphaericus JG-B53 19,20. Tuttavia, non all microbi legano elevate quantità di metalli e la loro applicazione come materiale sorbitive è limitato 12,21. Inoltre, la capacità di legame del metallo dipende da diversi parametri, ad esempio, la composizione delle cellule, il bio-componente utilizzato, o ambientali e condizioni sperimentali (pH, forza ionica, temperatura etc.). Lo studio di frammenti di parete cellulare isolati 22,23, come lipidi di membrana, peptidoglicano, proteine ​​o altri componenti, aiuta a comprendere il processo di complessi costruiti cellule intere 8,21 vincolante metallo. I componenti cellulari focalizzati su in questo studio sono proteine ​​S-layer. Proteine ​​S-strato sono parti della busta esterna delle cellule di molti batteri e di archeobatteri, e costituiscono circa il 15 - 20% della massa di proteine ​​totali di questi organismi. Come la prima interfaccia per l&#39;ambiente, questi composti cellulari influenzano fortemente le proprietà di assorbimento batteriche 3. Proteine ​​S-strato con peso molecolare compreso tra quarantaa centinaia di kDa sono prodotti all&#39;interno della cellula, ma sono montati all&#39;esterno dove sono in grado di formare strati sulle membrane lipidiche o componenti della parete cellulare polimerici. Una volta isolato, quasi tutti S-layer proteine ​​hanno la proprietà intrinseca di auto-assemblarsi spontaneamente in sospensione, alle interfacce, o su superfici che formano strutture planari o tube-like 3. Lo spessore del monostrato proteine ​​dipende batteri ed è in un intervallo di 5 - 25 nm 24. In generale, le strutture proteiche S-strato formato può avere un obliquo (P1 o P2), quadrato (P4), o esagonale (p3 o p6) simmetria con costanti reticolari 2,5 a 35 nm 3,24. La formazione reticolare sembra essere in molti casi dipendono cationi bivalenti e principalmente su Ca 2+ 25,26, Raff, J. et al. S-layer a base di nanocompositi per applicazioni industriali a base di proteine ​​Engineered Nanostructures. (a cura di Tijana Z. Grove &amp; Aitziber L. Cortajarena) (Springer, 2016 (presentato)). Tuttavia, la cascata reazione piena di monomero piegatura, interazione monomero-monomero, la formazione di un reticolo, e il ruolo dei diversi metalli, in particolare di cationi bivalenti come Ca 2+ e Mg 2+, non sono ancora del tutto chiaro. Il ceppo gram-positivi L. sphaericus JG-B53 (rinominato da Bacillus sphaericus dopo nuova classificazione filogenetica) 27 è stato isolato dalla miniera di uranio rifiuti mucchio &quot;Haberland&quot; (Johanngeorgenstadt, Sassonia, Germania) 4,28,29. La sua funzionale proteina S-layer (SLP1) possiede un reticolo quadrato, un peso molecolare di 116 kDa 30, e uno spessore di ≈ 10 nm a vivere cellule batteriche 31. In studi precedenti, la formazione in vitro di uno strato proteico chiuso e stabile con uno spessore di circa 10 nm è stato raggiunto in meno di 10 min 19. Il ceppo correlate L. sphaericus JG-A12, anche un isolato dal mucchio &quot;Haberland&quot;, possiede alta metallo capacità di legame e il suo isolato proteina S-layer ha mostrato un buon tasso di assorbimento chimica e stabilità meccanica e per i metalli preziosi come Au (III), Pt (II), e Pd (II) 4,32,33. Questo legame di metalli preziosi è più o meno specifici per alcuni metalli e dipende dalla disponibilità di gruppi funzionali sulla superficie esterna della proteina e interna del polimero e nei suoi pori, forza ionica, e il valore del pH. Gruppi funzionali rilevanti per l&#39;interazione metallo da parte delle proteine ​​sono COOH-, NH 2 -, OH-, PO 4 -, SO 4 - e SO-. In linea di principio, capacità di legame metallo aprono un ampio spettro di applicazioni, Raff, J. et al. S-layer a base di nanocompositi per applicazioni industriali a base di proteine ​​Engineered Nanostructures. (a cura di Tijana Z. Grove &amp; Aitziber L. Cortajarena) (Springer, 2016 (presentato)). ad esempio, come componenti biosorptive per la rimozione o recuperodi metalli tossici o pregiati disciolti, i modelli per sintesi o la deposizione di nanoparticelle definito regolarmente strutturati metalliche (NP) per la catalisi, e altri materiali bio-ingegneria, come bio-sensoriali strati 3,5,18,33. Array NP regolarmente organizzati come Au (0) -NPs potrebbero essere utilizzati per le principali applicazioni che spaziano dall&#39;elettronica molecolare e biosensori, dispositivi di storage ad altissima densità, e catalizzatori per CO-ossidazione 34-37. Lo sviluppo di tali applicazioni e design intelligente di questi materiali richiede una comprensione più profonda dei meccanismi vincolanti metallo sottostante. Un prerequisito per lo sviluppo di tali materiali bio-based è l&#39;implementazione affidabile di un livello di interfaccia tra la biomolecola e la superficie tecnica 38,39. Ad esempio, polielettroliti assemblati con il layer-by-layer (LBL) 40,41 tecnica sono stati utilizzati come strato di interfaccia per ricristallizzazione proteine ​​S-strato 39 </sup&gt;. Tale interfaccia offre un modo relativamente semplice per eseguire il rivestimento proteico in modo riproducibile e quantitativa. Eseguendo esperimenti diversi con e senza modifiche con i promotori adesive, è possibile fare dichiarazioni riguardanti la cinetica di rivestimento, la stabilità strato, e l&#39;interazione dei metalli con biomolecole 19,42, Raff, J. et al. S-layer a base di nanocompositi per applicazioni industriali a base di proteine ​​Engineered Nanostructures. (a cura di Tijana Z. Grove &amp; Aitziber L. Cortajarena) (Springer, 2016 (presentato)). Tuttavia, il complesso meccanismo di adsorbimento di proteine ​​e interazione proteina-superficie non è completamente noto. Soprattutto informazioni sulla conformazione, l&#39;orientamento del modello, e la densità di rivestimento è ancora mancante. Cristallo di quarzo microbilancia con il monitoraggio di dissipazione (QCM-D) la tecnica ha attirato l&#39;attenzione negli ultimi anni come uno strumento per lo studio delle proteine, la cinetica di rivestimento, e l&#39;interazione proprocessi su scala nanometrica 19,43-45. Questa tecnica permette di rilevare dettagliata di adsorbimento di massa in tempo reale, e può essere utilizzato come indicatore per il processo di auto-assemblaggio di proteine ​​e di accoppiamento molecole funzionali su reticoli proteine ​​19,20,42,46-48. Inoltre, le misure QCM-D aperta la possibilità di studiare processi di interazione del metallo con lo strato proteico in condizioni biologiche naturali. In un recente studio, l&#39;interazione della proteina S-strato con metalli scelti come Eu (III), Au (III), Pd (II) e Pt (II) è stato studiato con QCM-D 19,20. Lo strato proteina adsorbita può servire come un modello semplificato di una parete cellulare di batteri gram-positivi. Lo studio di questo singolo componente può contribuire a una più profonda comprensione delle interazioni metallo. Tuttavia, esclusivamente QCM-D esperimenti non consentono dichiarazioni riguardanti strutture superficiali e le influenze dei metalli alle proteine. Altre tecniche sono necessarie per ottenere tali informazioni. Una posbilità per immagini bio-nanostrutture e informazioni sulle proprietà strutturali ottenere è la microscopia a forza atomica (AFM). L&#39;obiettivo dello studio presentato era studiare l&#39;assorbimento di oro (Au (III) e Au (0) -NPs) alle proteine ​​S-strato, in particolare SLP1 di L. sphaericus JG-B53. Gli esperimenti sono stati fatti con proteine ​​sospesi su scala batch in un intervallo di pH di 2,0 - 5,0 mediante ICP-MS e con immobilizzati S livelli utilizzando QCM-D. Inoltre, l&#39;influenza della soluzione di sale di metallo sulla stabilità lattice è stata studiata con successivi studi AFM. La combinazione di queste tecniche contribuisce a una migliore comprensione dei processi di interazione in vitro in metallo come strumento per saperne di più su eventi in cellule batteriche intere riguardanti affinità metalliche specifiche vincolanti. Questa conoscenza non è solo cruciale per lo sviluppo di materiali filtranti applicabili per il recupero di metalli per la tutela dell&#39;ambiente e la conservazione del reFonti 49, ma anche per lo sviluppo di array di NP metalliche altamente ordinati per varie applicazioni tecniche.

<table><tbody><tr><td>&lt;strong&gt;equiment and software&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Bioreactor, Steam In Place 70L Pilot System</td><td>Applikon Biotechnology, Netherlands</td><td>Z6X</td><td>Including dO&lt;sub&gt;2&lt;/sub&gt;, pH sensors of Applikon Biotechnology and BioXpert software V2</td></tr><tr><td>Noninvasive Biomass Monitor BugEye 2100</td><td>BugLab, Concord (CA), USA</td><td>Z9X</td><td>---</td></tr><tr><td>Spectrometer Ultrospec 1000</td><td>Amersham Pharmacia Biotech, Great Britain</td><td>80-2109-10</td><td>Company now GE Healthcare Life Sciences</td></tr><tr><td>MiniStar micro centrifuge</td><td>VWR, Germany</td><td>521-2844</td><td>For centrifugation of cultivation samples</td></tr><tr><td>Research system microscope BX-61</td><td>Olympus Germany LLC, Germany</td><td>037006</td><td>Microscope in combination with imaging software</td></tr><tr><td>Cell^P (version 3.1)</td><td>Olympus Soft Imaging Solutions LLC, M&amp;uuml;nster, Germany</td><td>---</td><td>together with microscope</td></tr><tr><td>Powerfuge Pilot Separation System Serie 9010-S</td><td>Carr Centritech, Florida, USA</td><td>9010PLT</td><td>For biomasse harvesting</td></tr><tr><td>T18 basic Ultra Turrax</td><td>IKA Labortechnik, Germany</td><td>431-2601</td><td>For flagella removal and sample homogenization</td></tr><tr><td>Sorvall Evolution RC Superspeed Centrifuge</td><td>Thermo Fisher Scientific, USA</td><td>728411</td><td>Used within protein isolation</td></tr><tr><td>Mobile high shear fluid processor, M-110EH-30 Pilot</td><td>Microfluidics, Massachusetts, USA</td><td>M110EH30K</td><td>Used for cell rupture</td></tr><tr><td>Alpha 1-4 LSC Freeze dryer</td><td>Martin Christ Freeze dryers LLC, Osterode, Germany</td><td>102041</td><td>---</td></tr><tr><td>UV-VIS spectrophotometry (NanoDrop 2000c)</td><td>Thermo Fisher Scientific, USA</td><td>91-ND-2000C-L</td><td>For determination of protein concentration</td></tr><tr><td>Mini-PROTEAN vertical electrophoresis chamber</td><td>Bio-Rad Laboratories GmbH, Munich, Germany</td><td>165-3322</td><td>For SDS-PAGE</td></tr><tr><td>VersaDoc Imaging System 3000</td><td>Bio-Rad Laboratories GmbH, Munich, Germany</td><td>1708030</td><td>Used for imaging of SDS-PAGE gels</td></tr><tr><td>ICP-MS Elan 9000</td><td>PerkinElmer, Waltham (MA), USA</td><td>N8120536</td><td>For determination of metal concentration</td></tr><tr><td>Zetasizer Nano ZS</td><td>Malvern Instruments, Worcestershire United Kingdom</td><td>ZEN3600</td><td>For determination of nanoparticle size</td></tr><tr><td>Q-Sense E4 device&amp;nbsp;</td><td>Q-Sense AB, Gothenburg, Sweden</td><td>QS-E4</td><td>ordered via LOT quantum design (software included with E4 platform)</td></tr><tr><td>Q-Soft 401 (data recording)</td><td>Q-Sense AB, Gothenburg, Sweden</td><td></td><td></td></tr><tr><td>Q-Tools 3 (data evaluation and modelling)</td><td>Q-Sense AB, Gothenburg, Sweden</td><td></td><td></td></tr><tr><td>QCM-D flow modules QFM&amp;nbsp;401&amp;nbsp;</td><td>Q-Sense AB, Gothenburg, Sweden</td><td>QS-QFM401</td><td>ordered via LOT quantum design</td></tr><tr><td>QSX&amp;nbsp;303 SiO&lt;sub&gt;2&lt;/sub&gt; piezoelectric AT-cut quartz sensors</td><td>Q-Sense AB, Gothenburg, Sweden</td><td>QS-QSX303</td><td>ordered via LOT quantum design</td></tr><tr><td>Ozone cleaning chamber</td><td>Bioforce Nanoscience, Ames (IA), USA</td><td>QS-ESA006</td><td>ordered via LOT quantum design</td></tr><tr><td>Atomic Force Microscope MFP-3D Bio AFM</td><td>Asylum Research, Santa Barbara (CA), USA</td><td>MFP-3DBio</td><td>AFM measurements and imaging software</td></tr><tr><td>Asylum Research AFM Software AR Version 120804+1223</td><td>Asylum Research, Santa Barbara (CA), USA</td><td>---</td><td>imaging software included in Cat. No. MFP-3DBio</td></tr><tr><td>Igor Version Pro 6.3.2.3 Software</td><td>WaveMetrics, Inc., USA</td><td>---</td><td>imaging software included in Cat. No. MFP-3DBio</td></tr><tr><td>BioHeater</td><td>Asylum Research, Santa Barbara (CA), USA</td><td>Bioheater</td><td>Sample heater for AFM measurements</td></tr><tr><td>Biolever mini cantilever,&amp;nbsp; BL-AC40TS-C2</td><td>Olympus Germany LLC, Germany</td><td>&amp;nbsp;BL-AC40TS-C2</td><td>Prefered cantilever for AFM measurements</td></tr><tr><td>WSxM 5.0 Develop 6.5 (2013)</td><td>Nanotec Electronica S.L. , Spain</td><td>freeware</td><td>Software for AFM analysis</td></tr><tr><td>&lt;strong&gt;Name&lt;/strong&gt;</td><td>&lt;strong&gt;Company&lt;/strong&gt;</td><td>&lt;strong&gt;Catalog Number&lt;/strong&gt;</td><td>&lt;strong&gt;Comments&lt;/strong&gt;</td></tr><tr><td>&lt;strong&gt;Detergents and other equiment&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>acidic acid, 100 %, p.A.</td><td>CARL ROTH GmbH+CO.KG</td><td>3738.5</td><td>Danger, flammable and corrosive liquid and vapour. Causes severe skin burns and eye damage.</td></tr><tr><td>Antifoam 204</td><td>Sigma-Aldrich Co. LLC.</td><td>A6426</td><td>For foam suppression</td></tr><tr><td>bromophenol blue, sodium salt</td><td>Sigma-Aldrich Co. LLC.</td><td>B5525</td><td>---</td></tr><tr><td>Coomassie Brilliant Blue R (C&lt;sub&gt;45&lt;/sub&gt;H&lt;sub&gt;44&lt;/sub&gt;N&lt;sub&gt;3&lt;/sub&gt;NaO&lt;sub&gt;7&lt;/sub&gt;S&lt;sub&gt;2&lt;/sub&gt;)</td><td>CARL ROTH GmbH+CO.KG</td><td>3862.1</td><td>---</td></tr><tr><td>Deoxyribonuclease II from porcine spleen</td><td>Sigma-Aldrich Co. LLC.</td><td>D4138</td><td>Typ IV , 2,000 - 6,000&amp;nbsp;Kunitz units/mg protein</td></tr><tr><td>Ethanol, 95%</td><td>VWR, Germany</td><td>20827.467</td><td>Danger, flammable</td></tr><tr><td>glycerine, p.A.</td><td>CARL ROTH GmbH+CO.KG</td><td>3783.1</td><td>---</td></tr><tr><td>Guanidine hydrochloride (GuHCl)</td><td>CARL ROTH GmbH+CO.KG</td><td>0037.1</td><td>---</td></tr><tr><td>Hellmanex III</td><td>Hellma GmbH &amp;amp; Co. KG</td><td>9-307-011-4-507</td><td>---</td></tr><tr><td>Hydrochloric acid (HCl) (37%)</td><td>CARL ROTH GmbH+CO.KG</td><td>4625.2</td><td>Danger; Corrosive, used for pH adjustment</td></tr><tr><td>Lysozyme from chicken egg white</td><td>Sigma-Aldrich Co. LLC.</td><td>L6876&amp;nbsp;</td><td>Lyophilized powder, protein = 90 %, = 40,000 units/mg protein (Sigma)&amp;nbsp;</td></tr><tr><td>Magnetic stirrer with heating,&amp;nbsp; MR 3000K</td><td>Heidolph Instruments GmbH &amp;amp; Co.KG, Germany</td><td>504.10100.00</td><td>Standard stirrer within experiment</td></tr><tr><td>NB-Media DM180</td><td>Mast Diagnostica GmbH</td><td>121800</td><td>---</td></tr><tr><td>Nitric acid (HNO&lt;sub&gt;3&lt;/sub&gt;)</td><td>CARL ROTH GmbH+CO.KG</td><td>HN50.1</td><td>Danger; Oxidizing, Corrosing</td></tr><tr><td>PageRuler Unstained Protein Ladder</td><td>ThermoScientific-Pierce</td><td>26614</td><td>---</td></tr><tr><td>Poly(sodium 4-styrenesulfonat) (PSS)</td><td>Sigma-Aldrich Co. LLC.</td><td>243051</td><td>Average Mw ~70,000</td></tr><tr><td>Polyethylenimine (PEI), branched</td><td>Sigma-Aldrich Co. LLC.</td><td>408727</td><td>Warning; Harmful, Irritant, Dangerous for the environment; average Mw ~25,000</td></tr><tr><td>Potassium carbonate anhydrous (K&lt;sub&gt;2&lt;/sub&gt;CO&lt;sub&gt;3&lt;/sub&gt;)</td><td>Sigma-Aldrich Co. LLC.</td><td>60108</td><td>Warning; Harmful</td></tr><tr><td>Ribonuclease A from bovine pancreas&amp;nbsp;</td><td>Sigma-Aldrich Co. LLC.</td><td>R5503</td><td>Type I-AS, 50 - 100 Kunitz units/mg protein&amp;nbsp;</td></tr><tr><td>Sodium azide (NaN&lt;sub&gt;3&lt;/sub&gt;)</td><td>Merck KGaA</td><td>106688</td><td>Danger; very toxic and Dangerous for the environment</td></tr><tr><td>Sodium chloride (NaCl)</td><td>CARL ROTH GmbH+CO.KG</td><td>3957.2</td><td>---</td></tr><tr><td>Sodium dodecyl sulfate (SDS)</td><td>Sigma-Aldrich Co. LLC.</td><td>L-5750</td><td>Danger; toxic</td></tr><tr><td>Sodium hydroxide (NaOH)</td><td>CARL ROTH GmbH+CO.KG</td><td>6771.1</td><td>Danger; Corrosive, used for pH regulation within cultivation and pH adjustment</td></tr><tr><td>Spectra/Por 6, Dialysis membrane, MWCO 50,000&amp;nbsp;</td><td>CARL ROTH GmbH+CO.KG</td><td>1893.1</td><td>---</td></tr><tr><td>Sulfuric acid (H&lt;sub&gt;2&lt;/sub&gt;SO&lt;sub&gt;4&lt;/sub&gt;)</td><td>CARL ROTH GmbH+CO.KG</td><td>HN52.2</td><td>Danger; Corrosive, used for pH regulation within cultivation</td></tr><tr><td>Tannic acid (C&lt;sub&gt;76&lt;/sub&gt;H&lt;sub&gt;52&lt;/sub&gt;O&lt;sub&gt;46&lt;/sub&gt;)</td><td>Sigma-Aldrich Co. LLC.</td><td>16201</td><td>---</td></tr><tr><td>TRIS HCl (C&lt;sub&gt;4&lt;/sub&gt;H&lt;sub&gt;11&lt;/sub&gt;NO&lt;sub&gt;3&lt;/sub&gt;HCl)</td><td>CARL ROTH GmbH+CO.KG</td><td>9090.2</td><td>---</td></tr><tr><td>Triton X-100</td><td>CARL ROTH GmbH+CO.KG</td><td>3051.3</td><td>Warning; Harmful, Dangerous for the environment</td></tr><tr><td>VIVASPIN 500, 50,000 MWCO Ultrafiltration tubes</td><td>Sartorius AG</td><td>VS0132</td><td>---</td></tr><tr><td>&amp;beta;-mercaptoethanol</td><td>Sigma-Aldrich Co. LLC.</td><td>M6250</td><td>Danger, toxic</td></tr></tbody></table>

au-interaction of slp1 polymers and monolayer from lysinibacillus sphaericus jg-b53 - qcm-d, icp-ms and afm as tools for biomolecule-metal studies

In this publication the gold sorption behavior of surface layer (S-layer) proteins (Slp1) of Lysinibacillus sphaericus JG-B53 is described. These biomolecules arrange in paracrystalline two-dimensional arrays on surfaces, bind metals, and are thus interesting for several biotechnical applications, such as biosorptive materials for the removal or recovery of different elements from the environment and industrial processes. The deposition of Au(0) nanoparticles on S-layers, either by S-layer directed synthesis 1 or adsorption of nanoparticles, opens new possibilities for diverse sensory applications. Although numerous studies have described the biosorptive properties of S-layers 2-5, a deeper understanding of protein-protein and protein-metal interaction still remains challenging. In the following study, inductively coupled mass spectrometry (ICP-MS) was used for the detection of metal sorption by suspended S-layers. This was correlated to measurements of quartz crystal microbalance with dissipation monitoring (QCM-D), which allows the online detection of proteinaceous monolayer formation and metal deposition, and thus, a more detailed understanding on metal binding.
The ICP-MS results indicated that the binding of Au(III) to the suspended S-layer polymers is pH dependent. The maximum binding of Au(III) was obtained at pH 4.0. The QCM-D investigations enabled the detection of Au(III) sorption as well as the deposition of Au(0)-NPs in real-time during the in situ experiments. Further, this method allowed studying the influence of metal binding on the protein lattice stability of Slp1. Structural properties and protein layer stability could be visualized directly after QCM-D experiment using atomic force microscopy (AFM). In conclusion, the combination of these different methods provides a deeper understanding of metal binding by bacterial S-layer proteins in suspension or as monolayers on either bacterial cells or recrystallized surfaces.

Coltivazione di microrganismi e SLP1 Caratterizzazione I dati registrati di crescita batterica indica la fine della fase di crescita esponenziale a circa 5 ore. Studi precedenti hanno dimostrato che SLP1 può essere isolato da questo punto di raccolta (4,36 g / L biomassa umida (≈ 1,45 g / L (BDW)) con una resa massima 19. Tuttavia, l&#39;ottimizzazione della coltivazione utilizzando componenti o ...

Watch this Scientific Journal Video about Au-Interaction of Slp1 Polymers and Monolayer from Lysinibacillus sphaericus JG-B53 - QCM-D, ICP-MS and AFM as Tools for Biomolecule-metal Studies at JoVE.com

Au-Interaction of Slp1 Polymers and Monolayer from Lysinibacillus sphaericus JG-B53 - QCM-D, ICP-MS and AFM as Tools for Biomolecule-metal Studies

To obtain basic information on the sorption and recycling of gold from aqueous systems the interaction of Au(III) and Au(0) nanoparticles on S-layer proteins were investigated. The sorption of protein polymers was investigated by ICP-MS and that of proteinaceous monolayers by QCM-D. Subsequent AFM enables the imaging of the nanostructures.

Au-Interazione di SLP1 Polimeri e monostrato da<em&gt; Lysinibacillus sphaericus</em&gt; JG-B53 - QCM-D, ICP-MS e AFM come strumenti di studi Biomolecule metallo

In this publication the gold sorption behavior of surface layer (S-layer) proteins (Slp1) of Lysinibacillus sphaericus JG-B53 is described. These ...

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Au-Interaction of Slp1 Polymers and Monolayer from Lysinibacillus sphaericus JG-B53 - QCM-D, ICP-MS and AFM as Tools for Biomolecule-metal Studies

11.3K Views.  Helmholtz-Zentrum Dresden-Rossendorf. To obtain basic information on the sorption and recycling of gold from aqueous systems the interaction of Au(III) and Au(0) nanoparticles on S-layer proteins were investigated. The sorption of protein polymers was investigated by ICP-MS and that of proteinaceous monolayers by QCM-D. Subsequent AFM enables the imaging of the nanostructures.

Video: Au-Interaction of Slp1 Polymers and Monolayer from Lysinibacillus sphaericus JG-B53 - QCM-D, ICP-MS and AFM as Tools for Biomolecule-metal Studies

In Situ SIMS and IR Spectroscopy of Well-defined Surfaces Prepared by Soft Landing of Mass-selected Ions

Soft landing of mass-selected ions onto surfaces is a powerful approach for the highly-controlled preparation of materials that are inaccessible using conventional synthesis techniques. Coupling soft landing with in situ characterization using secondary ion mass spectrometry (SIMS) and infrared reflection absorption spectroscopy (IRRAS) enables analysis of well-defined surfaces under clean vacuum conditions. The capabilities of three soft-landing instruments constructed in our laboratory are illustrated for the representative system of surface-bound organometallics prepared by soft landing of mass-selected ruthenium tris(bipyridine) dications, [Ru(bpy)3]2+ (bpy = bipyridine), onto carboxylic acid terminated self-assembled monolayer surfaces on gold (COOH-SAMs). In situ time-of-flight (TOF)-SIMS provides insight into the reactivity of the soft-landed ions. In addition, the kinetics of charge reduction, neutralization and desorption occurring on the COOH-SAM both during and after ion soft landing are studied using in situ Fourier transform ion cyclotron resonance (FT-ICR)-SIMS measurements. In situ IRRAS experiments provide insight into how the structure of organic ligands surrounding metal centers is perturbed through immobilization of organometallic ions on COOH-SAM surfaces by soft landing. Collectively, the three instruments provide complementary information about the chemical composition, reactivity and structure of well-defined species supported on surfaces.

In Situ SIMS and IR Spectroscopy of Well-defined Surfaces Prepared by Soft Landing of Mass-selected Ions

Soft landing of mass-selected ions onto surfaces is a powerful approach for the highly-controlled preparation of novel materials. Coupled with analysis by in situ secondary ion mass spectrometry (SIMS) and infrared reflection absorption spectroscopy (IRRAS), soft landing provides unprecedented insights into the interactions of well-defined species with surfaces.

In Situ SIMS e IR Spettroscopia di superfici ben definite Preparato da atterraggio morbido di ioni Mass-selezionati

Soft landing of mass-selected ions onto surfaces is a powerful approach for the highly-controlled preparation of materials that are inaccessible using ...

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Chimica

Investigating Single Molecule Adhesion by Atomic Force Spectroscopy

Atomic force spectroscopy is an ideal tool to study molecules at surfaces and interfaces. An experimental protocol to couple a large variety of single molecules covalently onto an AFM tip is presented. At the same time the AFM tip is passivated to prevent unspecific interactions between the tip and the substrate, which is a prerequisite to study single molecules attached to the AFM tip. Analyses to determine the adhesion force, the adhesion length, and the free energy of these molecules on solid surfaces and bio-interfaces are shortly presented and external references for further reading are provided. Example molecules are the poly(amino acid) polytyrosine, the graft polymer PI-g-PS and the phospholipid POPE (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine). These molecules are desorbed from different surfaces like CH3-SAMs, hydrogen terminated diamond and supported lipid bilayers under various solvent conditions. Finally, the advantages of force spectroscopic single molecule experiments are discussed including means to decide if truly a single molecule has been studied in the experiment.

A protocol to couple a large variety of single molecules covalently onto an AFM tip is presented. Procedures and examples to determine the adhesion force and free energy of these molecules on solid supports and bio-interfaces are provided.

Indagare singola molecola di adesione da Atomic Spectroscopy Forza

Atomic force spectroscopy is an ideal tool to study molecules at surfaces and interfaces. An experimental protocol to couple a large variety of single ...

Ingegneria

Analyzing Dynamic Protein Complexes Assembled On and Released From Biolayer Interferometry Biosensor Using Mass Spectrometry and Electron Microscopy

In vivo, proteins are often part of large macromolecular complexes where binding specificity and dynamics ultimately dictate functional outputs. In this work, the pre-endosomal anthrax toxin is assembled and transitioned into the endosomal complex. First, the N-terminal domain of a cysteine mutant lethal factor (LFN) is attached to a biolayer interferometry (BLI) biosensor through disulfide coupling in an optimal orientation, allowing protective antigen (PA) prepore to bind (Kd 1 nM). The optimally oriented LFN-PAprepore complex then binds to soluble capillary morphogenic gene-2 (CMG2) cell surface receptor (Kd 170 pM), resulting in a representative anthrax pre-endosomal complex, stable at pH 7.5. This assembled complex is then subjected to acidification (pH 5.0) representative of the late endosome environment to transition the PAprepore into the membrane inserted pore state. This PApore state results in a weakened binding between the CMG2 receptor and the LFN-PApore and a substantial dissociation of CMG2 from the transition pore. The thio-attachment of LFN to the biosensor surface is easily reversed by dithiothreitol. Reduction on the BLI biosensor surface releases the LFN-PAprepore-CMG2 ternary complex or the acid transitioned LFN-PApore complexes into microliter volumes. Released complexes are then visualized and identified using electron microscopy and mass spectrometry. These experiments demonstrate how to monitor the kinetic assembly/disassembly of specific protein complexes using label-free BLI methodologies and evaluate the structure and identity of these BLI assembled complexes by electron microscopy and mass spectrometry, respectively, using easy-to-replicate sequential procedures.

Here we present a protocol to monitor the assembly and disassembly of the anthrax toxin using biolayer interferometry (BLI). Following assembly/disassembly on the biosensor surface, the large protein complexes are released from the surface for visualization and identification of components of the complexes using electron microscopy and mass spectrometry, respectively.

L'analisi di complessi proteici dinamico montato su e rilasciato da Biolayer interferometria biosensore utilizzando la microscopia elettronica e spettrometria di massa

In vivo, proteins are often part of large macromolecular complexes where binding specificity and dynamics ultimately dictate functional outputs. In this ...

Biochimica

Dissipative Microgravimetry to Study the Binding Dynamics of the Phospholipid Binding Protein Annexin A2 to Solid-supported Lipid Bilayers Using a Quartz Resonator

The dissipative quartz crystal microbalance technique is a simple and label-free approach to measure simultaneously the mass uptake and viscoelastic properties of the absorbed/immobilized mass on sensor surfaces, allowing the measurements of the interaction of proteins with solid-supported surfaces, such as lipid bilayers, in real-time and with a high sensitivity. Annexins are a highly conserved group of phospholipid-binding proteins that interact reversibly with the negatively charged headgroups via the coordination of calcium ions. Here, we describe a protocol that was employed to quantitatively analyze the binding of annexin A2 (AnxA2) to planar lipid bilayers prepared on the surface of a quartz sensor. This protocol is optimized to obtain robust and reproducible data and includes a detailed step-by-step description. The method can be applied to other membrane-binding proteins and bilayer compositions.

Here, we present an experimental protocol that can be employed to determine the binding affinities and mode of interaction of label-free phospholipid-binding protein annexin A2 with immobilized solid-supported bilayers (SLB) by simultaneously measuring the mass uptake and the viscoelastic properties of the protein annexin A2.

Microgravimetry dissipativo per studiare la dinamica di associazione del fosfolipide proteina Annessina A2 a lipidici solido-supportato utilizzando un risonatore al quarzo

The dissipative quartz crystal microbalance technique is a simple and label-free approach to measure simultaneously the mass uptake and viscoelastic ...

Insights into the Interactions of Amino Acids and Peptides with Inorganic Materials Using Single-Molecule Force Spectroscopy

The interactions between proteins or peptides and inorganic materials lead to several interesting processes. For example, combining proteins with minerals leads to the formation of composite materials with unique properties. In addition, the undesirable process of biofouling is initiated by the adsorption of biomolecules, mainly proteins, on surfaces. This organic layer is an adhesion layer for bacteria and allows them to interact with the surface. Understanding the fundamental forces that govern the interactions at the organic-inorganic interface is therefore important for many areas of research and could lead to the design of new materials for optical, mechanical and biomedical applications. This paper demonstrates a single-molecule force spectroscopy technique that utilizes an AFM to measure the adhesion force between either peptides or amino acids and well-defined inorganic surfaces. This technique involves a protocol for attaching the biomolecule to the AFM tip through a covalent flexible linker and single-molecule force spectroscopy measurements by atomic force microscope. In addition, an analysis of these measurements is included.

Here we present a protocol to measure the force of interactions between a well-defined inorganic surface and either peptides or amino acids by single-molecule force spectroscopy measurements using an atomic force microscope (AFM). The information obtained from the measurement is important to better understand the peptide-inorganic material interphase.

Intuizioni le interazioni di aminoacidi e peptidi con materiali inorganici Uso singola molecola Forza Spettroscopia

The interactions between proteins or peptides and inorganic materials lead to several interesting processes. For example, combining proteins with minerals ...

OaAEP1-Mediated Enzymatic Synthesis and Immobilization of Polymerized Protein for Single-Molecule Force Spectroscopy

Chemical and bio-conjugation techniques have been developed rapidly in recent years and allow the building of protein polymers. However, a controlled protein polymerization process is always a challenge. Here, we have developed an enzymatic methodology for constructing polymerized protein step by step in a rationally-controlled sequence. In this method, the C-terminus of a protein monomer is NGL for protein conjugation using OaAEP1 (Oldenlandia affinis asparaginyl endopeptidases) 1) while the N-terminus was a cleavable TEV (tobacco etch virus) cleavage site plus an L (ENLYFQ/GL) for temporary N-terminal protecting. Consequently, OaAEP1 was able to add only one protein monomer at a time, and then the TEV protease cleaved the N-terminus between Q and G to expose the NH2-Gly-Leu. Then the unit is ready for next OaAEP1 ligation. The engineered polyprotein is examined by unfolding individual protein domain using atomic force microscopy-based single-molecule force spectroscopy (AFM-SMFS). Therefore, this study provides a useful strategy for polyprotein engineering and immobilization.

Here, we present a protocol to conjugate protein monomer by enzymes forming protein polymer with a controlled sequence and immobilize it on the surface for single-molecule force spectroscopy studies.

Sintesi enzimatica mediata OaAEP1 e immobilizzazione delle proteine polimerizzate per la spettroscopia a singola molecola

Chemical and bio-conjugation techniques have been developed rapidly in recent years and allow the building of protein polymers. However, a controlled ...

Atomic Force Microscopy Imaging and Force Spectroscopy of Supported Lipid Bilayers

Atomic force microscopy (AFM) is a versatile, high-resolution imaging technique that allows visualization of biological membranes. It has sufficient magnification to examine membrane substructures and even individual molecules. AFM can act as a force probe to measure interactions and mechanical properties of membranes. Supported lipid bilayers are conventionally used as membrane models in AFM studies. In this protocol, we demonstrate how to prepare supported bilayers and characterize their structure and mechanical properties using AFM. These include bilayer thickness and breakthrough force. 
The information provided by AFM imaging and force spectroscopy help define mechanical and chemical properties of membranes. These properties play an important role in cellular processes such as maintaining cell hemostasis from environmental stress, bringing membrane proteins together, and stabilizing protein complexes.

We describe a protocol for preparation of supported lipid bilayers and its characterization using atomic force microscopy and force spectroscopy.

Atomic Force Microscopy Imaging e Spettroscopia Forza supportati doppi strati lipidici

Atomic force microscopy (AFM) is a versatile, high-resolution imaging technique that allows visualization of biological membranes. It has sufficient ...

Bioingegneria

Single Molecule Fluorescence Microscopy on Planar Supported Bilayers

In the course of a single decade single molecule microscopy has changed from being a secluded domain shared merely by physicists with a strong background in optics and laser physics to a discipline that is now enjoying vivid attention by life-scientists of all venues 1. This is because single molecule imaging has the unique potential to reveal protein behavior in situ in living cells and uncover cellular organization with unprecedented resolution below the diffraction limit of visible light 2. Glass-supported planar lipid bilayers (SLBs) are a powerful tool to bring cells otherwise growing in suspension in close enough proximity to the glass slide so that they can be readily imaged in noise-reduced Total Internal Reflection illumination mode 3,4. They are very useful to study the protein dynamics in plasma membrane-associated events as diverse as cell-cell contact formation, endocytosis, exocytosis and immune recognition. Simple procedures are presented how to generate highly mobile protein-functionalized SLBs in a reproducible manner, how to determine protein mobility within and how to measure protein densities with the use of single molecule detection. It is shown how to construct a cost-efficient single molecule microscopy system with TIRF illumination capabilities and how to operate it in the experiment.

Preparation of protein-functionalized planar glass-supported lipid bilayers, determination of protein mobility within and measurement of protein densities is shown here. A roadmap to building a noise-reduced Total Internal Reflection microscope is outlined, which allows visualizing single bilayer-resident fluorochromes with high spatiotemporal resolution.

Singola molecola microscopia a fluorescenza su Planar bilayers supportati

In the course of a single decade single molecule microscopy has changed from being a secluded domain shared merely by physicists with a strong background ...

Covalent Attachment of Single Molecules for AFM-based Force Spectroscopy

Atomic force microscopy (AFM)-based single molecule force spectroscopy is an ideal tool for investigating the interactions between a single polymer and surfaces. For a true single molecule experiment, covalent attachment of the probe molecule is essential because only then can hundreds of force-extension traces with one and the same single molecule be obtained. Many traces are in turn necessary to prove that a single molecule alone is probed. Additionally, passivation is crucial for preventing unwanted interactions between the single probe molecule and the AFM cantilever tip as well as between the AFM cantilever tip and the underlying surface. The functionalization protocol presented here is reliable and can easily be applied to a variety of polymers. Characteristic single molecule events (i.e., stretches and plateaus) are detected in the force-extension traces. From these events, physical parameters such as stretching force, desorption force and desorption length can be obtained. This is particularly important for the precise investigation of stimuli-responsive systems at the single molecule level. As exemplary systems poly(ethylene glycol) (PEG), poly(N-isopropylacrylamide) (PNiPAM) and polystyrene (PS) are stretched and desorbed from SiOx (for PEG and PNiPAM) and from hydrophobic self-assembled monolayer surfaces (for PS) in aqueous environment.

Covalent attachment of probe molecules to atomic force microscopy (AFM) cantilever tips is an essential technique for the investigation of their physical properties. This allows us to determine the stretching force, desorption force and length of polymers via AFM-based single molecule force spectroscopy with high reproducibility.

Attacco covalente di singole molecole per la spettroscopia della forza basata su AFM

Atomic force microscopy (AFM)-based single molecule force spectroscopy is an ideal tool for investigating the interactions between a single polymer and ...

Ligand Nano-cluster Arrays in a Supported Lipid Bilayer

Currently there is considerable interest in creating ordered arrays of adhesive protein islands in a sea of passivated surface for cell biological studies. In the past years, it has become increasingly clear that living cells respond, not only to the biochemical nature of the molecules presented to them but also to the way these molecules are presented. Creating protein micro-patterns is therefore now standard in many biology laboratories; nano-patterns are also more accessible. However, in the context of cell-cell interactions, there is a need to pattern not only proteins but also lipid bilayers. Such dual proteo-lipidic patterning has so far not been easily accessible. We offer a facile technique to create protein nano-dots supported on glass and propose a method to backfill the inter-dot space with a supported lipid bilayer (SLB). From photo-bleaching of tracer fluorescent lipids included in the SLB, we demonstrate that the bilayer exhibits considerable in-plane fluidity. Functionalizing the protein dots with fluorescent groups allows us to image them and to show that they are ordered in a regular hexagonal lattice. The typical dot size is about 800 nm and the spacing demonstrated here is 2 microns. These substrates are expected to serve as useful platforms for cell adhesion, migration and mechano-sensing studies.

We present a protocol to functionalize glass with nanometric protein patches surrounded by a fluid lipid bilayer. These substrates are compatible with advanced optical microscopy and are expected to serve as platform for cell adhesion and migration studies.

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