This study was supported by grants from the intramural innovative medical research program of Muenster University medical faculty (KE121201 to C.K.) and the German Research Foundation (DFG, Fo354/3-1 to D.F.).

NOTE: Please refer to Supplemental Table 1 for preparation of buffers and stock solutions.
1. Protein expression in E. coli
<ol>
	<li>Cloning
	<ol>
		<li>Clone tag-free human S100A12 (NCBI Reference Sequence: NP_005612.1) into bacterial expression vector pET11b. To express the protein, transform the construct into E. coli BL21(DE3).</li>
	</ol>
	</li>
	<li>Culture
	<ol>
		<li>Prepare a starter culture by in...

<ol>
	<li>Liston, A., Masters, S. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Homeostasis-altering+molecular+processes+as+mechanisms+of+inflammasome+activation.">Homeostasis-altering molecular processes as mechanisms of inflammasome activation.</a> Nature Reviews Immunology. 17 (3), 208-214 (2017).</li><li>Kessel, C., Holzinger, D., Foell, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phagocyte-derived+S100+proteins+in+autoinflammation:+putative+role+in+pathogenesis+and+usefulness+as+biomarkers.">Phagocyte-derived S100 proteins in autoinflammation: putative role in pathogenesis and usefulness as biomarkers.</a> Clinical Immunology. 147 (3), 229-241 (2013).</li><li>Baker, T. M., Nakashige, T. G., Nolan, E. M., Neidig, M. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Magnetic+circular+dichroism+studies+of+iron(ii)+binding+to+human+calprotectin.">Magnetic circular dichroism studies of iron(ii) binding to human calprotectin.</a> Chemical Science. 8 (2), 1369-1377 (2017).</li><li>Nakashige, T. G., Zhang, B., Krebs, C., Nolan, E. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+calprotectin+is+an+iron-sequestering+host-defense+protein.">Human calprotectin is an iron-sequestering host-defense protein.</a> Nature Chemical Biology. 11 (10), 765-771 (2015).</li><li>Nakashige, T. G., Zygiel, E. M., Drennan, C. L., Nolan, E. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nickel+Sequestration+by+the+Host-Defense+Protein+Human+Calprotectin.">Nickel Sequestration by the Host-Defense Protein Human Calprotectin.</a> Journal of the American Chemical Society. 139 (26), 8828-8836 (2017).</li><li>Cunden, L. S., Gaillard, A., Nolan, E. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Calcium+Ions+Tune+the+Zinc-Sequestering+Properties+and+Antimicrobial+Activity+of+Human+S100A12.">Calcium Ions Tune the Zinc-Sequestering Properties and Antimicrobial Activity of Human S100A12.</a> Chemical Science. 7 (2), 1338-1348 (2016).</li><li>Moroz, O. V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structure+of+the+human+S100A12-copper+complex:+implications+for+host-parasite+defence.">Structure of the human S100A12-copper complex: implications for host-parasite defence.</a> Acta Crystallographica Section D, Biological Crystallography. 59 (Pt 5), 859-867 (2003).</li><li>Moroz, O. V., Blagova, E. V., Wilkinson, A. J., Wilson, K. S., Bronstein, I. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+crystal+structures+of+human+S100A12+in+apo+form+and+in+complex+with+zinc:+new+insights+into+S100A12+oligomerisation.">The crystal structures of human S100A12 in apo form and in complex with zinc: new insights into S100A12 oligomerisation.</a> Journal of Molecular Biology. 391 (3), 536-551 (2009).</li><li>Korndorfer, I. P., Brueckner, F., Skerra, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+crystal+structure+of+the+human+(S100A8/S100A9)2+heterotetramer,+calprotectin,+illustrates+how+conformational+changes+of+interacting+alpha-helices+can+determine+specific+association+of+two+EF-hand+proteins.">The crystal structure of the human (S100A8/S100A9)2 heterotetramer, calprotectin, illustrates how conformational changes of interacting alpha-helices can determine specific association of two EF-hand proteins.</a> Journal of Molecular Biology. 370 (5), 887-898 (2007).</li><li>Moroz, O. V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Both+Ca2++and+Zn2++are+essential+for+S100A12+protein+oligomerization+and+function.">Both Ca2+ and Zn2+ are essential for S100A12 protein oligomerization and function.</a> BMC Biochemistry. 10, 11 (2009).</li><li>Baudier, J., Glasser, N., Gerard, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ions+binding+to+S100+proteins.+I.+Calcium-+and+zinc-binding+properties+of+bovine+brain+S100+alpha+alpha,+S100a+(alpha+beta),+and+S100b+(beta+beta)+protein:+Zn2++regulates+Ca2++binding+on+S100b+protein.">Ions binding to S100 proteins. I. Calcium- and zinc-binding properties of bovine brain S100 alpha alpha, S100a (alpha beta), and S100b (beta beta) protein: Zn2+ regulates Ca2+ binding on S100b protein.</a> Journal of Biological Chemistry. 261 (18), 8192-8203 (1986).</li><li>Dell&#8217;Angelica, E. C., Schleicher, C. H., Santome, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Primary+structure+and+binding+properties+of+calgranulin+C,+a+novel+S100-like+calcium-binding+protein+from+pig+granulocytes.">Primary structure and binding properties of calgranulin C, a novel S100-like calcium-binding protein from pig granulocytes.</a> Journal of Biological Chemistry. 269 (46), 28929-28936 (1994).</li><li>Vogl, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=S100A12+is+expressed+exclusively+by+granulocytes+and+acts+independently+from+MRP8+and+MRP14.">S100A12 is expressed exclusively by granulocytes and acts independently from MRP8 and MRP14.</a> Journal of Biological Chemistry. 274 (36), 25291-25296 (1999).</li><li>Hofmann, M. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=RAGE+mediates+a+novel+proinflammatory+axis:+a+central+cell+surface+receptor+for+S100/calgranulin+polypeptides.">RAGE mediates a novel proinflammatory axis: a central cell surface receptor for S100/calgranulin polypeptides.</a> Cell. 97 (7), 889-901 (1999).</li><li>Foell, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Proinflammatory+S100A12+Can+Activate+Human+Monocytes+via+Toll-like+Receptor+4.">Proinflammatory S100A12 Can Activate Human Monocytes via Toll-like Receptor 4.</a> American Journal of Respiratory and Critical Care Medicine. 187 (12), 1324-1334 (2013).</li><li>Kessel, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Calcium+and+zinc+tune+autoinflammatory+Toll-like+receptor+4+signaling+by+S100A12.">Calcium and zinc tune autoinflammatory Toll-like receptor 4 signaling by S100A12.</a> Journal of Allergy and Clinical Immunology. 142 (4), 1370-1373 (2018).</li><li>Armaroli, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monocyte-Derived+Interleukin-1beta+As+the+Driver+of+S100A12-Induced+Sterile+Inflammatory+Activation+of+Human+Coronary+Artery+Endothelial+Cells:+Implications+for+the+Pathogenesis+of+Kawasaki+Disease.">Monocyte-Derived Interleukin-1beta As the Driver of S100A12-Induced Sterile Inflammatory Activation of Human Coronary Artery Endothelial Cells: Implications for the Pathogenesis of Kawasaki Disease.</a> Arthritis &amp; Rheumatology. 71 (5), 792-804 (2019).</li><li>GE Healthcare. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Strategies for Protein Purification. Handbook. , (2010).</li><li>Jackson, E., Little, S., Franklin, D. S., Gaddy, J. A., Damo, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Expression,+Purification,+and+Antimicrobial+Activity+of+S100A12.">Expression, Purification, and Antimicrobial Activity of S100A12.</a> Journal of Visualized Experiments. (123), (2017).</li><li>Kiss, B., Ecsedi, P., Simon, M., Nyitray, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+and+Characterization+of+S100+Protein-Protein+Complexes.">Isolation and Characterization of S100 Protein-Protein Complexes.</a> Methods in Molecular Biology. 1929, 325-338 (2019).</li><li>Magalhaes, P. O., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methods+of+endotoxin+removal+from+biological+preparations:+a+review.">Methods of endotoxin removal from biological preparations: a review.</a> Journal of Pharmacy and Pharmaceutical Sciences. 10 (3), 388-404 (2007).</li><li>Petsch, D., Anspach, F. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endotoxin+removal+from+protein+solutions.">Endotoxin removal from protein solutions.</a> Journal of Biotechnology. 76 (2-3), 97-119 (2000).</li><li>Heilmann, R. M., Suchodolski, J. S., Steiner, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Purification+and+partial+characterization+of+canine+S100A12.">Purification and partial characterization of canine S100A12.</a> Biochimie. 92 (12), 1914-1922 (2010).</li><li>Hung, K. W., Hsu, C. C., Yu, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Solution+structure+of+human+Ca2+-bound+S100A12.">Solution structure of human Ca2+-bound S100A12.</a> Journal of Biomolecular NMR. 57 (3), 313-318 (2013).</li><li>Endotoxin Removal. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Application Note - Sartorius Stedim Biotech. , (2010).</li><li>Hogasen, A. K. M., Abrahamsen, T. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polymyxin-B+Stimulates+Production+of+Complement+Components+and+Cytokines+in+Human+Monocytes.">Polymyxin-B Stimulates Production of Complement Components and Cytokines in Human Monocytes.</a> Antimicrobial Agents and Chemotherapy. 39 (2), 529-532 (1995).</li><li>Valentinis, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+effects+of+polymyxin+B+on+human+dendritic+cells+maturation+-+The+role+of+I+kappa+B-alpha/NF-kappa+B+and+ERK1/2+pathways+and+adhesion.">Direct effects of polymyxin B on human dendritic cells maturation - The role of I kappa B-alpha/NF-kappa B and ERK1/2 pathways and adhesion.</a> Journal of Biological Chemistry. 280 (14), 14264-14271 (2005).</li><li>Teuber, M., Miller, I. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Selective+Binding+of+Polymyxin-B+to+Negatively+Charged+Lipid+Monolayers.">Selective Binding of Polymyxin-B to Negatively Charged Lipid Monolayers.</a> Biochimica Et Biophysica Acta. 467 (3), 280-289 (1977).</li></ol>

In this protocol, we describe tag-free bacterial expression of human S100A12 and its purification as well as separation into different ion-induced oligomers for immune cell stimulation. Compared to published literature on S100A12 protein purification8,23,24, the use of high CaCl2 (25 mM) in hydrophobic-interaction chromatography is to our knowledge unique. Several protocols applying concentrations from 1 to 5 mM do pr...

S100A12 is a calcium binding protein which is predominantly produced by human granulocytes. The protein is overexpressed during (systemic) inflammation and its serum levels, particularly in (auto)inflammatory diseases such as systemic juvenile idiopathic arthritis (sJIA), familial Mediterranean fever (FMF) or Kawasaki disease (KD) can inform about disease activity and response to therapy. Depending on pattern recognition receptors (PRRs) such as toll-like receptors (TLRs), the innate immune system can be activated by pathogen-associated molecular patterns (PAMPs) like lipopolysaccharides (LPS) or damage associated molecular patterns (DAMPs; also termed &#8216;alarmins&#8217;). DAMPs are endogenous molecules such as cellular proteins, lipids or nucleic acids1. DAMP-functions are well described for the members of the calgranulin protein family, S100A8/A9 and S100A122, which are also reported to operate as divalent metal ion-chelating antimicrobial peptides3,4,5,6. Depending on the available ion strength S100A12 can, like other members of the S100 family, arrange into different homomultimers and until recently the impact of S100A12-oligomerisation on PRR-interaction, particularly TLR4, was unknown.
The protein&#8217;s monomeric form (92 amino acids, 10.2 kDa) consists of two EF-hand helix-loop-helix structures connected by a flexible linker. The C-terminal EF-hand contains the classical Ca2+-binding motif whereas the N-terminal EF-hand exhibits an S100 protein-specific extended loop structure (&#8216;pseudo-EF-hand&#8217;) and reveals reduced Ca2+-affinity. Ca2+-binding by S100A12 can induce a major conformational change in the proteins&#8217; C-terminus, which results in exposure of a hydrophobic patch on each monomer and forms the dimerization interface. Thus, under physiological conditions, the smallest quaternary structure formed by S100A12 is a non-covalent dimer (approximately 21 kDa) in which individual monomers are in antiparallel orientation. When arranged as dimer, S100A12 is reported to sequester Zn2+ as well as other divalent metal ions, e.g., Cu2+ with high affinity7. These ions are coordinated at the S100A12 dimer interface by amino acids H15 and D25 of one subunit and H85 as well as H89 of the anti-paralleling other subunit8,9,10. While earlier studies propose that Zn2+-loaded S100A12 may induce the protein&#8217;s organization into homo-tetramers (44 kDa) and to result in increased Ca2+-affinity11,12, recent metal titration studies6 suggest Ca2+-binding by S100A12 to increase the protein&#8217;s affinity to Zn2+. Once the S100A12 EF-hands are fully occupied by Ca2+, additional Ca2+ is thought to bind between dimers, triggering hexamer formation (approximately 63 kDa). The architecture of the hexameric quarternary structure is clearly different from that of the tetramer. It is proposed that the tetramer interface is disrupted to give rise to new dimer-dimer interfaces which benefits hexamer formation10. S100A12 is almost exclusively expressed by human granulocytes where it constitutes about 5% of all cytosolic protein13. In its DAMP function S100A12 was historically described as agonist of the multi-ligand receptor for advanced glycation end-products (RAGE), then termed extracellular newly identified RAGE-binding protein (EN-RAGE)14. Albeit we earlier reported biochemical S100A12-binding to both RAGE and TLR415, we recently demonstrated human monocytes to respond to S100A12 stimulation in a TLR4-dependent manner16. This requires arrangement of S100A12 into its Ca2+/Zn2+-induced hexameric quarternary structure16.
Here we describe a purification procedure for recombinant human S100A12 and its ion-induced oligomers for immune cell stimulations16,17. This is based on a two-step chromatography strategy, which initially includes an anion-exchange column to isolate and concentrate the protein and remove bulk contaminations (e.g., endotoxins/lipopolysaccharides)18. Ion-exchange chromatography resins separate proteins on the basis of different net surface charges. For acidic proteins like S100A12 (isoelectric point of 5.81), a buffer system with a pH of 8.5 and a strong anion-exchange resin leads to a good separation. Bound proteins were eluted with a high-salt buffer gradient. With an increase of ionic strength negative ions in the elution buffer compete with proteins for charges on the surface of the resin. Proteins individually elute depending on their net charge and in result of that, the buffers described herein allow to isolate and concentrate the overexpressed S100A12 protein. Due to negatively charged groups in lipopolysaccharides, these molecules also bind to anion-exchange resins. However, their higher net charge results in later elution in the applied high-salt gradient. The second step of the purification procedure has been introduced for polishing purposes. This makes use of the calcium binding ability of S100A12 and removes remaining impurities on a hydrophobic-interaction column. Calcium binding of S100A12 leads to a conformational change and an exposure of hydrophobic patches on the surface of the protein. On that condition, S100A12 interacts with the hydrophobic surface of the resin. Upon calcium-chelating by EDTA, this interaction is reversed. In the presence of ions, especially calcium and zinc, S100A12 arranges into homomeric oligomers. To study structure-function relationships of the different oligomers, we stabilized dimeric, tetrameric and hexameric recombinant S100A12 with a chemical crosslinker and separated the complexes on a size-exclusion chromatography column. Finally, to analyze functionality and biological activity of the purified protein and its ion-induced oligomers, the cytokine release of S100A12 and LPS stimulated monocyte can be compared.
Various methods for purifying S100A12 have been described so far. Jackson et al.19, for example, published a protocol with purification via an anion-exchange column and a subsequent size-exclusion chromatography. Purification polishing on a size-exclusion column leads to good results, but&#8213;due to for example limited loading volumes&#8213;is less flexible in scalability. A different approach, published by Kiss et al.20, describes purification of tagged protein via Ni2+ affinity column as the first purification step, followed by enzymatic cleavage to remove the tag and further purification steps. In contrast to the aforecited studies19,20, the produced protein as described in this protocol is determined for experiments on immune cells. Therefore, remnant endotoxin contamination from bacterial culture is a challenge. Although different approaches for endotoxin removal have been described so far, there is no uniform method that works equally well for any given protein solution21,22.
In summary, our protocol combines the advantages of a tag-free expression in a bacterial system with efficient endotoxin removal and high yield of pure protein.

<table>
	<tbody>
		<tr>
			<td>pET11b vector</td>
			<td>Novagen</td>
			<td>&#160;</td>
			<td>&#160;</td>
		</tr>
		<tr>
			<td>BL21(DE3) competent E. coli</td>
			<td>New England Biolabs</td>
			<td>C2527</td>
			<td>&#160;</td>
		</tr>
		<tr>
			<td>&#160;</td>
			<td>&#160;</td>
			<td>&#160;</td>
			<td>&#160;</td>
		</tr>
		<tr>
			<td>100 x Non-essential amino acids</td>
			<td>Merck</td>
			<td>K 0293</td>
			<td></td>
		</tr>
		<tr>
			<td>25% HCl</td>
			<td>Carl Roth</td>
			<td>X897.1</td>
			<td></td>
		</tr>
		<tr>
			<td>4&#8722;20% Mini-PROTEAN TGX Protein Gels</td>
			<td>BioRad</td>
			<td>4561093</td>
			<td></td>
		</tr>
		<tr>
			<td>Ampicillin sodium salt</td>
			<td>Carl Roth</td>
			<td>HP62.1</td>
			<td></td>
		</tr>
		<tr>
			<td>BS3 (bis(sulfosuccinimidyl)suberate) - 50 mg</td>
			<td>ThermoFisher Scientific</td>
			<td>21580</td>
			<td></td>
		</tr>
		<tr>
			<td>Calciumchlorid Dihydrat</td>
			<td>Carl Roth</td>
			<td>5239.1</td>
			<td></td>
		</tr>
		<tr>
			<td>Coomassie Briliant Blue R250 Destaining Solution</td>
			<td>BioRad</td>
			<td>1610438</td>
			<td></td>
		</tr>
		<tr>
			<td>Coomassie Briliant Blue R250 Staining Solution</td>
			<td>BioRad</td>
			<td>1610436</td>
			<td></td>
		</tr>
		<tr>
			<td>EasySep Human Monocyte Enrichment Kit</td>
			<td>Stemcell</td>
			<td>19059</td>
			<td>Magnetic negative cell isolation kit</td>
		</tr>
		<tr>
			<td>EDTA disodium salt dihydrate</td>
			<td>Carl Roth</td>
			<td>8043.1</td>
			<td></td>
		</tr>
		<tr>
			<td>EGTA</td>
			<td>Carl Roth</td>
			<td>3054.3</td>
			<td></td>
		</tr>
		<tr>
			<td>EndoLISA</td>
			<td>Hyglos</td>
			<td>609033</td>
			<td>Endotoxin detection assay</td>
		</tr>
		<tr>
			<td>Endotoxin-Free Ultra Pure Water</td>
			<td>Sigma-Aldrich</td>
			<td>TMS-011-A</td>
			<td>Ultrapure water for preparation of endotoxin-free buffers</td>
		</tr>
		<tr>
			<td>EndoTrap red</td>
			<td>Hyglos</td>
			<td>321063</td>
			<td>Endotoxin removal resin</td>
		</tr>
		<tr>
			<td>FBS (heat-inactivated)</td>
			<td>Gibco</td>
			<td>10270</td>
			<td></td>
		</tr>
		<tr>
			<td>HBSS, no calcium, no magnesium</td>
			<td>ThermoFisher Scientific</td>
			<td>14175053</td>
			<td></td>
		</tr>
		<tr>
			<td>Hepes</td>
			<td>Carl Roth</td>
			<td>9105</td>
			<td></td>
		</tr>
		<tr>
			<td>Hepes (high quality, endotoxin testet)</td>
			<td>Sigma-Aldrich</td>
			<td>H4034</td>
			<td></td>
		</tr>
		<tr>
			<td>hTNF-alpha - OptEia ELISA Set</td>
			<td>BD</td>
			<td>555212</td>
			<td></td>
		</tr>
		<tr>
			<td>IPTG (isopropyl-&#223;-D-thiogalactopyranosid)</td>
			<td>Carl Roth</td>
			<td>CN08.1</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Glutamine (200 mM)</td>
			<td>Merck</td>
			<td>K 0282</td>
			<td></td>
		</tr>
		<tr>
			<td>LB-Medium</td>
			<td>Carl Roth</td>
			<td>X968.1</td>
			<td></td>
		</tr>
		<tr>
			<td>Lipopolysaccharides from E. coli O55:B5</td>
			<td>Merck</td>
			<td>L6529</td>
			<td></td>
		</tr>
		<tr>
			<td>Pancoll, human</td>
			<td>PAN Biotech</td>
			<td>P04-60500</td>
			<td>Separation solution (density gradient centrifugation)</td>
		</tr>
		<tr>
			<td>Penicillin/Streptomycin (10.000 U/ml)</td>
			<td>Merck</td>
			<td>A 2212</td>
			<td></td>
		</tr>
		<tr>
			<td>Phenyl Sepharose High Performance</td>
			<td>GE Healthcare</td>
			<td>17-1082-01</td>
			<td>Resin for hydrophobic interaction chromatography</td>
		</tr>
		<tr>
			<td>Polymyxin B</td>
			<td>Invivogen</td>
			<td>tlrl-pmb</td>
			<td></td>
		</tr>
		<tr>
			<td>Protease inhibitor tablets</td>
			<td>Roche</td>
			<td>11873580001</td>
			<td></td>
		</tr>
		<tr>
			<td>Q Sepharose Fast Flow</td>
			<td>GE Healthcare</td>
			<td>17-0510-01</td>
			<td>Resin for anion-exchange chromatography</td>
		</tr>
		<tr>
			<td>RoboSep buffer</td>
			<td>Stemcell</td>
			<td>20104</td>
			<td>Cell separation buffer (section 5.1.4)</td>
		</tr>
		<tr>
			<td>RPMI 1640 Medium</td>
			<td>Merck</td>
			<td>F 1215</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium chloride (NaCl)</td>
			<td>Carl Roth</td>
			<td>3957.2</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium hydroxide</td>
			<td>Carl Roth</td>
			<td>P031.1</td>
			<td></td>
		</tr>
		<tr>
			<td>Tris Base</td>
			<td>Carl Roth</td>
			<td>4855.3</td>
			<td></td>
		</tr>
		<tr>
			<td>Zinc chloride</td>
			<td>Carl Roth</td>
			<td>T887</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Labware</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>0,45 &#181;m syringe filter</td>
			<td>Merck</td>
			<td>SLHA033SS</td>
			<td></td>
		</tr>
		<tr>
			<td>14 mL roundbottom tubes</td>
			<td>BD</td>
			<td>352059</td>
			<td></td>
		</tr>
		<tr>
			<td>2 L Erlenmyer flask</td>
			<td>Carl Roth</td>
			<td>LY98.1</td>
			<td></td>
		</tr>
		<tr>
			<td>24 well suspension plates</td>
			<td>Greiner</td>
			<td>662102</td>
			<td></td>
		</tr>
		<tr>
			<td>5 L measuring beaker</td>
			<td>Carl Roth</td>
			<td>CKN3.1</td>
			<td></td>
		</tr>
		<tr>
			<td>50 mL conical centrifuge tubes</td>
			<td>Corning</td>
			<td>430829</td>
			<td></td>
		</tr>
		<tr>
			<td>50 mL high-speed centrifuge tubes</td>
			<td>Eppendorf</td>
			<td>3,01,22,178</td>
			<td></td>
		</tr>
		<tr>
			<td>Amicon Ultra-15 Centrifugal Filter Unit MWCO 3 kDa</td>
			<td>Merck</td>
			<td>UFC900324</td>
			<td></td>
		</tr>
		<tr>
			<td>Amicon Ultra-15 Centrifugal Filter Unit MWCO 50 kDa</td>
			<td>Merck</td>
			<td>UFC905024</td>
			<td></td>
		</tr>
		<tr>
			<td>Culture dish (100 mm)</td>
			<td>Sarstedt</td>
			<td>83.3902</td>
			<td></td>
		</tr>
		<tr>
			<td>Dialysis Tubing Closures</td>
			<td>Spectrum</td>
			<td>132738</td>
			<td></td>
		</tr>
		<tr>
			<td>EasySep magnet &#39;The Big Easy`</td>
			<td>Stemcell</td>
			<td>18001</td>
			<td></td>
		</tr>
		<tr>
			<td>Fraction collector tubes 5 mL</td>
			<td>Greiner</td>
			<td>115101</td>
			<td></td>
		</tr>
		<tr>
			<td>Lumox film, 25 &#181;m, 305 mm x 40 m</td>
			<td>Sarstedt</td>
			<td>94,60,77,316</td>
			<td>Film for monocyte culture plates</td>
		</tr>
		<tr>
			<td>Spectra/Por Dialysis Membrane (3.5 kDa)</td>
			<td>Spectrum</td>
			<td>132724</td>
			<td></td>
		</tr>
		<tr>
			<td>Steritop filter unit</td>
			<td>Merck</td>
			<td>SCGPT01RE</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Equipment</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>37 &#176;C Incubator (with shaking)</td>
			<td>New Brunswick Scientific</td>
			<td>Innova 42</td>
			<td></td>
		</tr>
		<tr>
			<td>&#196;KTA purifier UPC 10</td>
			<td>GE Healthcare</td>
			<td></td>
			<td>FPLC System</td>
		</tr>
		<tr>
			<td>Fraction collector</td>
			<td>GE Healthcare</td>
			<td>Frac-920</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge (with rotor A-4-81)</td>
			<td>Eppendorf</td>
			<td>5810R</td>
			<td></td>
		</tr>
		<tr>
			<td>Fixed angle rotor</td>
			<td>Eppendorf</td>
			<td>F-34-6-38</td>
			<td></td>
		</tr>
		<tr>
			<td>Mini Protean Tetra Cell</td>
			<td>BioRad</td>
			<td>1658000EDU</td>
			<td></td>
		</tr>
		<tr>
			<td>NanoPhotometer</td>
			<td>Implen</td>
			<td>P330</td>
			<td></td>
		</tr>
		<tr>
			<td>Sonicator</td>
			<td>Brandelin</td>
			<td>UW2070</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorescence reader</td>
			<td>Tecan</td>
			<td>infinite M200PRO</td>
			<td></td>
		</tr>
		<tr>
			<td>pH meter</td>
			<td>Knick</td>
			<td>765</td>
			<td></td>
		</tr>
	</tbody>
</table>

purification of human s100a12 and its ion-induced oligomers for immune cell stimulation

In this protocol, we describe a method to purify human calcium-binding protein S100A12 and its ion-induced oligomers from Escherichia coli culture for immune cell stimulations. This protocol is based on a two-step chromatography strategy, which comprises protein pre-purification on an anion-exchange chromatography column and a subsequent polishing step on a hydrophobic-interaction column. This strategy produces S100A12 protein of high purity and yield at manageable costs. For functional assays on immune cells eventual remnant endotoxin contamination requires careful monitoring and further cleaning steps to obtain endotoxin-free protein. The majority of endotoxin contaminations can be excluded by anion-exchange chromatography. To deplete residual contaminations, this protocol describes a removal step with centrifugal filters. Depending on the available ion-strength S100A12 can arrange into different homomultimers. To investigate the relationship between structure and function, this protocol further describes ion-treatment of S100A12 protein followed by chemical crosslinking to stabilize S100A12 oligomers and their subsequent separation by size-exclusion chromatography. Finally, we describe a cell-based assay that confirms the biological activity of the purified protein and confirms LPS-free preparation.

Following pre-purification on the AIEX column (Figure 1A-C) and subsequent calcium-dependent HIC (Figure 2A,B), highly pure protein was obtained (Figure 2C). In addition, measurements of endotoxin revealed successful LPS removal. The LPS content following AIEX was measured in a 1:10 dilution above the assay detection limit, i.e., above 500 EU/mL. After the first filtration through a 50 kDa filter un...

Watch this Scientific Journal Video about Purification of Human S100A12 and Its Ion-induced Oligomers for Immune Cell Stimulation at JoVE.com

Purification of Human S100A12 and Its Ion-induced Oligomers for Immune Cell Stimulation

This protocol describes a purification method for recombinant tag-free calcium binding protein S100A12 and its ion-induced oligomers for human monocyte stimulation assays.

In this protocol, we describe a method to purify human calcium-binding protein S100A12 and its ion-induced oligomers from Escherichia coli culture for ...

This protocol describes a complete purification procedure for the human calcium binding protein, S100A12, and in particular, for it's different ion-induced oligomers for downstream research implications. With this technique, we are able to maintain high yield of very pure and endotoxin-free protein. Chemical cross-linking and separation on the size exclusion chromatography column is a convincing method to generate homo-oligomeric proteins for further functional assays.Our technique allows us to mechanistic aspects of S100A12 as pattern recognition receptor ligand and art information to ideally develop new targeted interventions and improve diagnostic assays. In addition to watching this video, we recommend a careful reading of the protocol, as we describe a complex, multi-step procedure. To begin, cut a dialysis tubing into an appropriate length, around 30 centimeters, with additional space for air.Soak the membrane in deionized water for 15 to 30 minutes to remove glycerol. To reduce the viscosity of the cleared protein solution, dilute the solution with 25 milliliters of AIEX buffer A.Attach the first closure onto the tubing. Load the sample into the membrane and attach the second closure at least one centimeter from the top end of the tubing.In a cooled room at four degrees Celsius, place the container with AIEX buffer A on a stir plate, add a stir bar, and the membrane filled with protein solution. Adjust the speed to rotate the sample so that there is no interference with the rotating stir bar. Dialyze for 12 to 24 hours at four degrees Celsius then replace the dialyzed buffer with free pre-cooled buffer A and continue for at least four additional hours.Transfer the dialyzed protein solution from the tubing into a 50 milliliter tube through a 0.45 micron filter unit. Start the FPLC with general maintenance. Connect column buffers AIEX A and AIEX B to buffer valves and anion exchange resin containing column to the column ports of the FPLC.Adjust the general chromatographic parameters accordingly. Start the AIEX program in the FPLC software and choose the equilibration volume for buffer A.Subsequently, load the sample onto the column and elute the proteins with a linear gradient from 0%to 100%high salt buffer. Collect two milliliter fractions during elution.Analyze the eluted fractions after finishing the run. For this, load 10 microliters of each fraction on a Coomassie stained 15%SDS page and identify fractions containing S100A12. Pool these S100A12 containing fractions for dialysis into TRIS-buffered saline.To continue the protein purification, after the protein dialysis, add a calcium chloride to the sample to a final concentration of 25 millimolar, which will facilitate binding of S100A12 to the resin in the next step. Then, filter the sample through a filter with a pour size of 0.45 microns. Equilibrate HIC buffers and samples to four degrees Celsius.Next, connect column buffers HIC A and B and the column to the system and adjust the parameters. Start the method to equilibrate the column with one to two column volumes of buffer HIC A and load the sample and the wash unbound sample block with a UV signal reaches baseline level again. Then start elution with a calcium chelator containing buffer EDTA.Collect two milliliters of peak fractions during elution. After analyzing 10 microliters of each fraction on a Coomassie stained 15%SDS page identify pure S100A12 fractions. Pool these fractions and dialyze against HBS.First, load 15 milliliters of sample onto a 50 kilodalton centrifugal filter unit. Centrifuge at 3200 times g at 10 degrees Celsius for approximately 10 minutes. Transfer the filtrated flow-through into a fresh vessel, on ice.Now, use one milliliter of HBS to rinse the filter membrane and for dilution of the concentrated solution in the filter tip. Centrifuge again to recover as much protein as possible in the flow-through. To filter the solution, repeat the sample loading and centrifugation as often as necessary.Next, to concentrate the S100A12 containing flow-through, load it into a three kilodalton centrifugal filter and centrifuge at 3200 times g, 10 degrees Celsius for approximately 30 minutes. Now the volume is reduced to 1/5 up to 1/10 of the initial loading volume. Transfer the concentrated solution to a new tube.Repeat the concentration step as often as necessary. After chemical cross-linking, according to the manuscript, perform size exclusion chromatography. Equilibrate the column in HBS, load the sample, and collect peak fractions of one to two milliliters during the run.After analyzing these fractions on a four to 20%gradient SDS page, pool fractions with major bands of the desired protein complex. Then concentrate the solutions as done previously. To isolate monocytes from human buffy coats by density gradient centrifugation, first equilibrate the separation solution to room temperature.Transfer 20 milliliters into 15 milliliter centrifuge tubes, two tubes per buffy coat. Dilute the blood from the human buffy coat with HBSS to a total volume of 60 milliliters and layer 30 milliliters of this mixture carefully on top of the separation medium. Centrifuge at 550 times g for 35 minutes at room temperature.Switch off the brake of the centrifuge. After centrifugation, the mononuclear peripheral blood cells are located directly on top of the separation medium. With a pipette, transfer these cells into a fresh, 50 milliliter centrifuge tube.Fill the tube with HBSS to 50 milliliters and centrifuge at 170 times g for 10 minutes. Aspirate the supernatant and resuspend the cell pellet in a small volume of HBSS by pipetting. Then, fill the tube up to 50 milliliters and centrifuge at 290 times g for 10 minutes.Aspirate the supernatant again. Resuspend the cells in 50 milliliters of HBSS and centrifuge at 170 times g for 10 minutes. Aspirate the supernatant and resuspend the cell pellet in a small volume of one milliliter of separation buffer, count the cells, and add buffer to a concentration of five times 10 to the seven cells per milliliter.For monocyte isolation from mononuclear peripheral blood cells, use a magnetic negative cell isolation kit and follow the manufacturer's protocol. Use an automated cell counter to count the monocytes and resuspend in monocyte medium to a concentration of two times 10 to the six cells per milliliter. To culture monocytes, lay out a cell culture dish with a hydrophobic gas permeable film suitable for suspension cells.Place the plates under UV light for approximately 30 minutes for sterilization. Transfer 15 to 25 milliliters of the cell suspension to these culture plates and let them rest overnight at 37 degrees Celsius and 5%carbon dioxide. Following pre-purification on the AIEX column and subsequent calcium dependent HIC, highly pure protein was obtained.As an additional control, human monocytes were stimulated with LPS and produced wild-type protein. Protein exposure to different ions results in arrangement of different S100A12 oligomers. Increasing zinc concentrations induce arrangement of S100A12 into tetramers and hexamers upon separation on four to 20%Coomassie stained SDS page.When an excess of ions was applied prior to cross-linking, it induced a pronounced shift of the oligomer equilibrium. S100A12 was cross-linked in the presence of either 25 millimolar calcium or 25 millimolar calcium and one millimolar zinc. After cross-linking in HBS buffer with 25 millimolar calcium chloride and one millimolar zinc chloride, hexamer and tetramer were separated.Tetramer and dimer were separated in HBS buffer with 25 millimolar calcium chloride. An example of pooled and concentrated oligomers after separation on a Coomassie stained four to 15%gradient SDS page shows dimer, tetramer, and hexamer. Monocyte stimulation with hexameric S100A12 resulted in pronounced TNF alpha release.After removal of endotoxin, it is important not to reintroduce contamination into the samples during subsequent generation and purification of the oligomers. Downstream analysis of any process that relates to S100A12 oligomerization is conceivable. Similarly, amino acids and ion conditions that affect the oligomerization process itself can be analyzed.We're currently using S100A12 oligomers separated according to the described protocol to develop specific peptide ligands and antibodies to block the protein's signaling through TLF4 and to develop and improve diagnostic assays.

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Immunology and Infection

5.8K Views.  University Children's Hospital. This protocol describes a complete purification procedure for the human calcium binding protein, S100A12, and in particular, for it's different ion-induced oligomers for downstream research implications. With this technique, we are able to maintain high yield of very pure and endotoxin-free protein. Chemical cross-linking and separation on the size exclusion chromatography column is a convincing method to generate homo-oligomeric proteins for further functional assays.Our technique all...