Esta pesquisa foi apoiada pelo Departamento de Veteranos Assuntos Carreira Desenvolvimento Award 1IK2BX001701, CTSA prêmio UL1TR000445 do Centro Nacional para o Avanço Translational Sciences, o National Science Foundation Award Números 1547757 e 1400969, e NIH concessão GM05551. Seu conteúdo é exclusivamente da responsabilidade dos autores e não representam necessariamente visões oficiais do Centro Nacional para o Avanço das Ciências Translacionais ou dos Institutos Nacionais de Saúde.

1. Expressão de S100A12 <ol><li> Transformar células BL21 DE3 competentes com um plasmídeo pGEMEX-S100a12 utilizando um protocolo padrão de choque térmico 18 . Adicionar 1 a 5 μL de plasmídeo a 50 μL de bactérias num tubo de microcentrífuga em gelo. Incubar durante 20 min. </li><li> Aquecer as células a 42 ° C durante 30 s. </li><li> Incubar as células em gelo durante 2 min. </li><li> Adicionar 500 μL de meio SOC às células. Incubar a 37 ° C com agitação a 250 rpm num agitador orbital durante 1 h. </li><li> Placa 150 μL da reação de transformação em meio LB-agar (suplementado com 100 μg / mL de ampicilina). Incubar durante 12-16 h a 37 ° C. </li><li> Escolha uma colônia. Inocular 2 mL de LB (suplementado com 100 μg / mL de ampicilina). </li><li> Incubar durante 4-6 h a 37 ° C num agitador orbital (300 rpm). A OD 600 deve ler entre 1-3 unidades de absorvância. </li><li> Adicionar 500 μL de cultura inicial a 50 mL de ZYM-5052 autoinduCtion 26 suplementado com 100 μg / mL de ampicilina. Para melhor arejamento e máxima expressão, use um frasco Erlenmeyer de 250 mL. Agitar (300 rpm) durante 24 h, a 37 ° C. </li><li> Transferir a suspensão bacteriana para um tubo de centrífuga. Pellet as células por centrifugação (4.000 xg, 10 min) a 4 ° C. </li><li> Decantar a mídia, registrar a amostra e armazenar a pasta celular a -80 ° C. A amostra é estável por anos. </li></ol> 2. Purificação de S100A12 utilizando cromatografia de baixa pressão <ol><li> Ressuspender as células em 30 mL de Tris 20 mM, pH 8,0. </li><li> Sonicate a suspensão em gelo para lisar células. Utilize ~ 20 W de saída, 5 s ligado e 5 s fora do ciclo durante 5 min. </li><li> Transferir a solução para tubos de centrífuga de alta velocidade. Esclarecer o lisado celular por centrifugação, 20.000 xg durante 30 min a 4 ° C. </li><li> Decantar o sobrenadante e transferir para um copo de polipropileno limpo de 100 mL. Arrefecer a solução colocando o copo em gelo. Adicionar uma agitaçãoR e adicionar lentamente 11,20 g de sulfato de amónio. Deixar a solução agitar sobre gelo durante mais 1 h. Isto irá criar uma solução a 60% de sulfato de amónio e precipitar a maioria das proteínas endógenas de E. coli . S100A12 permanecerá solúvel. </li><li> Centrifugar a solução a 4 ° C, 20 000 xg durante 20 minutos para sedimentar a proteína precipitada. </li><li> Decantar o sobrenadante e transferir para tubos de diálise (MWCO 3.500 kDa). Dializar contra 1 L de Tris 20 mM, pH 8,0 a 4 ° C. Mude o tampão de diálise duas vezes. Permitir 4 h entre as alterações. </li><li> Cromatografia de permuta aniónica <ol><li> Realizar a cromatografia em um sistema de baixa pressão. O caudal típico é de 1 mL / min. </li><li> Equilibrar uma coluna de 5 mL de Sepharose com 10 mL de Tris 20 mM, pH 8,0. </li><li> Coloque os ~ 40 mL de solução de S100A12 usando a bomba de amostra (colete o fluxo através). </li><li> Lavar a coluna com 10 mL de Tris 20 mM, pH 8. </li><li> Desenvolver a coluna com um gradiente 0-30% (BuFfer B é Tris 20 mM, pH 8,0, NaCl 1 M) ao longo de 19 volumes de coluna (CV, 95 mL). Recolher fracções de 5 mL. </li><li> Tomar uma alíquota de 10 μL de cada fracção e analisar utilizando MES SDS PAGE com coloração Coomassie. Executar o gel utilizando uma tensão constante (20 V / cm) durante 30 min. </li><li> Pool fracções contendo S100A12. S100A12 corre a ~ 10 kDa de proteína num gel desnaturante. </li><li> Concentrar as fracções para 5 mL utilizando um dispositivo de ultrafiltração (MWCO 10 kDa). Centrifugar a 3000 xg durante ~ 8 min. Pegue a fração superior. </li></ol></li><li> Cromatografia de exclusão de tamanho <ol><li> Equilibrar a coluna S75 com 1 CV (120 mL) de Tris 20 mM pH 8, NaCl 100 mM. </li><li> Injectar &lt;5 mL de fracções S100A12 concentradas (a partir da cromatografia de permuta iónica). </li><li> Desenvolver a coluna a um caudal de 1 mL / m em 120 mL. Recolher fracções de 5 mL. </li><li> Tomar uma alíquota de 10 μL de cada fracção e analisar utilizando SDS PAGE com coloração com Coomassie. Validar a identidade proteica usandoWestern blot ou espectrometria de massa (massa molecular calculada da subunidade monomérica 10,575.0 Da, medida 10575,4 Da). </li></ol></li><li> Frações de pool <ol><li> Medir a absorvï¿½cia da proteï¿½a A 280 utilizando um espectrofotï¿½etro. Use o buffer SEC como um espaço em branco. O coeficiente de extinção calculado para o homodímero S100A12 é 5960 M -1 cm -1 . NOTA: Rendimentos típicos são 35-45 mg de S100A12 por 50 mL de cultura. </li><li> Alíquota S100A12 em tubos de microcentrífuga de 1,5 mL (1 mg / tubo), congelamento rápido em azoto líquido e armazenar a -80 ° C. </li></ol></li></ol> 3. Ensaios de actividade antimicrobiana <ol><li> Colocar a estirpe G27 de H. pylori sobre placas de ágar de soja trípticas suplementadas com sangue de ovelha a 5% (placas de ágar sangue). Crescer 2-3 dias a 37 ° C em ar ambiente suplementado com 5% de dióxido de carbono. </li><li> Inocular H. pylori em caldo de Brucella suplementado com 1x colesterol. Cultura sobreAgitação noturna (250 rpm) a 37 ° C em ar ambiente suplementado com 5% de dióxido de carbono. </li><li> Diluir H. pylori 1:10 em 50% de caldo de Brucella, 50% de tampão de calprotectina mais 1x colesterol e cultura em meio isolado ou suplementado com 100 μM de cloreto de zinco mais 0, 100 ou 1000 μg / mL de S100A12 purificado. Cultura agitação durante a noite (250 rpm) a 37 ° C em ar ambiente suplementado com 5% de dióxido de carbono. </li><li> No dia seguinte, efectuar diluições em série e placa sobre placas de agar de sangue. Deixar as colónias bacterianas crescerem durante 2-3 dias a 37 ° C em ar ambiente suplementado com 5% de dióxido de carbono. Enumerar as unidades formadoras de colónias para calcular o crescimento bacteriano na presença ou ausência de S100A12 e / ou zinco exógeno. </li></ol>

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Os autores declaram que não têm interesses financeiros concorrentes.

É apresentado um protocolo eficiente para expressão e purificação de S100A12 humano. O sistema de expressão de E. coli é a ferramenta mais comum usada para a produção de proteínas recombinantes, particularmente quando são necessárias quantidades de mg para estudos bioquímicos e biofísicos. Um aperfeiçoamento chave do procedimento aqui descrito é o uso de meios de auto-indução 26 que aumenta o rendimento da proteína purificada por um factor de quase trinta em comparaçã...

As proteï¿½as S100 sï¿½ uma classe da famï¿½ia EF-hand de proteï¿½as de ligaï¿½o de cï¿½cio com uma diversidade de funï¿½es 1 . Eles são expressos de uma forma específica de tecidos e células, e regulam um amplo espectro de funções celulares 2 , 3 . Exclusivas para proteínas de ligação ao cálcio, as proteínas S100 exibem funções intracelulares e extracelulares 4 , 5 . Dentro da célula, a ligação de Ca2 + induz uma alteração conformacional que expõe uma superfície hidrofóbica que alveja especificamente parceiros de ligação à proteína 6 . Este mecanismo intracelular regula processos importantes como proliferação celular, diferenciação e metabolismo energético. No meio extracelular, as proteínas S100 exibem duas funções 7 . Num deles, actuam como proteínas associadas a padrões moleculares associados (DAMP) e iniciam uma pró-inflamaçãoResposta imune atórica através da interação com receptores de reconhecimento de padrão 8 , 9 . Além disso, vários membros da classe de proteínas S100 sequestam metais de transição, uma função que serve para privar patógenos microbianos em um processo denominado imunidade nutricional 10 , 11 . S100A12 (também conhecida como calgranulina C e EN-RAGE) é altamente expressa em macrófagos e neutrófilos e tem sido identificada como potencial biomarcador para doenças inflamatórias 12,13 . Além de ligar o cálcio nos seus locais EF-Hand, S100A12 tem dois locais de ligação de metais de transição de alta afinidade localizados em extremidades opostas da interface dimérica 14 , 15 . Cada sítio de ligação é constituído por três resíduos de histidina e um resíduo de ácido aspártico e pode quelar zinco ou cobre &lt;Sup class = &quot;xref&quot;&gt; 16 , 17 . Recentemente, relatamos que a fome de zinco dependente de S100A12 é importante na regulação do crescimento de Helicobacter pylori e da atividade de fatores de virulência pró-inflamatórios 18 . H. pylori infecta o estômago de cerca de metade da população humana do mundo; Tornando-se sem dúvida um dos mais bem sucedidos patógenos bacterianos [ 19] . A infecção com H. pylori pode levar a resultados significativos da doença gástrica incluindo gastrite, úlcera péptica e duodenal, linfoma de tecido linfóide associado à mucosa (MALT) e adenocarcinoma gástrico invasivo (câncer de estômago). O câncer de estômago é a principal causa de morte associada ao câncer de não-cardia no mundo, eo maior fator de risco associado para câncer de estômago é a infecção por H. pylori . H. pylori persiste no nicho gástrico apesar de um robuSt resposta imune ao patógeno, sublinhando a necessidade de uma melhor compreensão dos mecanismos imunes de controle desta infecção bacteriana 20 , 21 , 22 , 23 . A inflamação associada ao H. pylori é caracterizada por uma profunda infiltração de células polimorfonucleares, ou neutrófilos, que depositam um repertório de proteínas antimicrobianas, incluindo S100A12, no local da infecção 18 , 24 , 25 . Em um esforço para entender o complexo diálogo entre hospedeiro e patógeno, buscamos refinar a técnica para purificar S100A12 e usá-lo para estudar o efeito antimicrobiano que exerce sobre este patógeno clinicamente relevante. O protocolo abaixo descreve uma técnica melhorada para a purificação de S100A12 no seu estado biologicamente activo; Capazes de se ligar a metais nutrientes com altaE eliminando-os de microrganismos invasores. Além disso, os métodos abaixo destacam a utilidade desta proteína como um reagente crítico para estudar o mecanismo pelo qual as moléculas antimicrobianas inatas restringem o crescimento de patógenos bacterianos. As proteínas da família S100A ganharam apreciação como um importante grupo de moléculas do sistema imune inatas que participam na sinalização imune bem como na defesa do hospedeiro 27 . O mais bem estudado destes é a calprotectina (MRP-8/14, calgranulina A / B, S100A8 / A9) 28 , 29 , 30 . A calprotectina é uma proteína associada a neutrófilos que forma um heterodímero das subunidades S100A8 e S100A9 que liga metais de transição na interface dímero 31 . Verificou-se que a calprotectina possui dois locais de ligação de metal: o local 1 pode ligar Zn2 + , Mn2 + ou Fe2 + e o sítio 2 pode<html> Se Zn2 + 31 , 32 . Numerosos relatos demonstraram que a calprotectina tem atividades antimicrobianas contra diversos agentes patogênicos incluindo Staphylococcus aureus , Candida albicans , Acinetobacter baumannii , Klebsiella pneumoniae , Escherichia coli e H. pylori e que os efeitos inibitórios são devidos à atividade de quelação de metal da calprotectina 25,28 , 29 . Trabalhos anteriores demonstraram que a calprotectina exerce numerosas atividades sobre H. pylori, incluindo a alteração da estrutura do lípido A na membrana externa, reprimindo o sistema de secreção tipo IV (que é um importante fator de virulência proinflamatório dentro de H. pylori ), induzindo a formação de biofilme e reprimindo Crescimento e viabilidade de H. pylori de uma forma dependente da doseClass = &quot;xref&quot;&gt; 25 , 33 . Além disso, os ensaios genéticos e bioquímicos revelaram que a actividade antibacteriana da calprotectina contra H. pylori foi largamente derivada da sua capacidade para ligar o zinco nutriente 25 . H. pylori requer zinco, como foi determinado por pesquisas anteriores, que utilizou um meio quimicamente definido para determinar os requisitos de micronutrientes para este patógeno para crescer e proliferar [ 34] . Além disso, a calprotectina foi altamente abundante nos tecidos infectados com H. pylori e associada a infiltrados neutrófilos, indicando que o hospedeiro pode empregar calprotectina como estratégia antimicrobiana durante a infecção e subseqüente inflamação 25,35. Evidências recentes de técnicas de triagem proteômica não-direcionadas sugerem que sob condições onde espécies reativas de oxigênio são abundantes, calprotecO estanho sofre modificações pós-translacionais que alteram o local de ligação da hexa-histidina, inibindo assim a actividade de ligação do metal da proteína 36 . Como tal, nós hipotetizamos que outras proteínas da família S100A entre o vasto repertório dessas moléculas poderiam potencialmente atuar como quelantes metálicos auxiliares. Seleccionou-se S100A12 para estudo adicional porque não foi identificado no referido ecrã para modificação pós-tradução, tem a capacidade de ligar o zinco e é altamente abundante em tecidos humanos derivados de indivíduos infectados com H. pylori . O nosso trabalho indica que S100A12 pode inibir o crescimento ea viabilidade de H. pylori de uma forma dependente da dose na estirpe G27 de H. pylori , e que a actividade antimicrobiana desta proteína pode ser invertida pela adição de zinco em excesso de nutrientes. Este trabalho complementa o nosso trabalho anterior indicando S100A12 exerceram atividade antimicrobiana contra PMSS1 e 7.13 de H. pylori , demonstrando sua ampla atividade antibacteriana contra numerosos isolados clínicos e linhagens de H. pylori adaptadas ao laboratório 18 . Juntos, estes resultados confirmam a importância de S100A12 como um mecanismo para controlar o crescimento bacteriano e proliferação via imunidade nutricional. Futuros estudos desta importante interacção hospedeiro-bactéria poderiam incluir explorar a actividade de S100A12 para reduzir a carga bacteriana dentro dos tecidos do hospedeiro ou determinar a contribuição desta proteína para a sinalização imune no contexto da infecção por H. pylori .

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>S100A12 Expression</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Expression cells</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>BL 21 (DE3) competent cells</td>
			<td>New England Biolabs</td>
			<td>C25271</td>
		</tr>
		<tr>
			<td>Autoinduction medium components</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Yeast Extract</td>
			<td>Research Products International</td>
			<td>Y20020-250.0</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Research Products International</td>
			<td>S23020-500.0</td>
		</tr>
		<tr>
			<td>Tryptone</td>
			<td>Research Products International</td>
			<td>T60060-250.0</td>
		</tr>
		<tr>
			<td>FeCl3</td>
			<td>Sigma-Aldrich</td>
			<td>F2877</td>
		</tr>
		<tr>
			<td>MgSO4</td>
			<td>Research Products International</td>
			<td>M65240-100.0</td>
		</tr>
		<tr>
			<td>Na2HPO4</td>
			<td>Research Products International</td>
			<td>S23100-500.0</td>
		</tr>
		<tr>
			<td>KH2PO4</td>
			<td>Research Products International</td>
			<td>P41200-500.0</td>
		</tr>
		<tr>
			<td>NH4Cl</td>
			<td>Research Products International</td>
			<td>A20424-500.0</td>
		</tr>
		<tr>
			<td>Na2SO4</td>
			<td>Research Products International</td>
			<td>S25150-500.0</td>
		</tr>
		<tr>
			<td>Glycerol</td>
			<td>Research Products International</td>
			<td>G22020-1.0</td>
		</tr>
		<tr>
			<td>D-glucose</td>
			<td>Research Products International</td>
			<td>G32040-500.0</td>
		</tr>
		<tr>
			<td>lactose</td>
			<td>Sigma-Aldrich</td>
			<td>L2643</td>
		</tr>
		<tr>
			<td>Selection agent</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>ampicillin</td>
			<td>Research Products International</td>
			<td>A40040-5.0</td>
		</tr>
		<tr>
			<td>S100A12 Purification</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>AKTA Start Chromatography System</td>
			<td>GE</td>
			<td>29-220-94</td>
		</tr>
		<tr>
			<td>HiTrap Q Sepharaose Fast Flow</td>
			<td>GE</td>
			<td>17-5156-01</td>
		</tr>
		<tr>
			<td>HiPrep 16/60 S-200 HR</td>
			<td>GE</td>
			<td>17-1166-01</td>
		</tr>
		<tr>
			<td>Nanodrop lite spectrophotometer</td>
			<td>Thermo Fisher Scientific</td>
			<td>ND-LITE</td>
		</tr>
		<tr>
			<td>Tris Base</td>
			<td>Research Products International</td>
			<td>T60040-1000.0</td>
		</tr>
		<tr>
			<td>H. pylori Culture</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Blood agar plates</td>
			<td>Lab Supply Company</td>
			<td>BBL221261</td>
		</tr>
		<tr>
			<td>Brucella broth</td>
			<td>Sigma-Aldrich</td>
			<td>B3051</td>
		</tr>
		<tr>
			<td>Cholesterol (250X)</td>
			<td>Thermo Fisher Scientific</td>
			<td>12531018</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Sigma-Aldrich</td>
			<td>793566</td>
		</tr>
		<tr>
			<td>CaCl2</td>
			<td>Sigma-Aldrich</td>
			<td>C4901</td>
		</tr>
		<tr>
			<td>&#946;-mercaptoethanol</td>
			<td>Sigma-Aldrich</td>
			<td>M6250</td>
		</tr>
		<tr>
			<td>Tris Base</td>
			<td>Sigma-Aldrich</td>
			<td>T1503</td>
		</tr>
		<tr>
			<td>Zinc Chloride</td>
			<td>Sigma-Aldrich</td>
			<td>229997</td>
		</tr>
	</tbody>
</table>

expression, purification, and antimicrobial activity of s100a12

As proteínas de calgranulina são mediadores importantes da imunidade inata e são membros da classe S100 da família EF-mão de proteínas de ligação de cálcio. Algumas proteínas S100 têm a capacidade de se ligar a metais de transição com alta afinidade e efetivamente seqüestrar eles longe de patógenos microbianos invasores em um processo que é denominado &quot;imunidade nutricional&quot;. O S100A12 (EN-RAGE) liga tanto o zinco como o cobre e é altamente abundante em células imunes inatas tais como macrófagos e neutrófilos. Relatamos um método refinado para a expressão, enriquecimento e purificação de S100A12 na sua configuração ativa de ligação a metais. A utilização desta proteína em análises de crescimento e viabilidade bacteriana revela que S100A12 tem actividade antimicrobiana contra o patogénio bacteriano Helicobacter pylori . A actividade antimicrobiana baseia-se na actividade de ligação ao zinco de S100A12, que quela o zinco nutriente, privando assim H. pylori que requer zinco para crescimento e pRoliferation.

S100A12 expressão e purificação Uma purificação em três passos produziu ~ 40 mg de S100A12 recombinante a partir de 50 mL de cultura bacteriana. O primeiro passo foi uma precipitação com sulfato de amónio de proteínas endógenas de E. coli . Este passo foi seguido por cromatografia de permuta aniónica ( Figura 1A ). A proteína é rastreada por uma SDS-PAGE corada com Coomassi...

Watch this Scientific Journal Video about Expression, Purification, and Antimicrobial Activity of S100A12 at JoVE.com

Expression, Purification, and Antimicrobial Activity of S100A12

Aqui, apresentamos um método para expressar e purificar S100A12 (calgranulina C). Descrevemos um protocolo para medir sua atividade antimicrobiana contra o patógeno humano H. pylori .

Expressão, Purificação e Actividade Antimicrobiana de S100A12

Calgranulin proteins are important mediators of innate immunity and are members of the S100 class of the EF-hand family of calcium binding proteins. Some ...

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8.3K visualizações.  Fisk University.  Aqui, apresentamos um método para expressar e purificar S100A12 (calgranulina C). Descrevemos um protocolo para medir sua atividade antimicrobiana contra o patógeno humano H. pylori . 

Vídeo: Expression, Purification, and Antimicrobial Activity of S100A12

Thermostabilization, Expression, Purification, and Crystallization of the Human Serotonin Transporter Bound to S-citalopram

The serotonin transporter is a sodium and chloride-coupled transporter that &#34;pumps&#34; extracellular serotonin into cells. S-citalopram is a drug used to treat depression and anxiety by binding to the serotonin transporter with high-affinity, blocking serotonin reuptake. Here we report an efficient procedure and a set of tools to stabilize, express, purify, and crystallize serotonin transporter-antibody complexes bound to S-citalopram and other antidepressants. Mutations which stabilize the serotonin transporter were identified using an S-citalopram binding assay. Serotonin transporter expressed in baculovirus-transduced HEK293S GnTI- cells, was reconstituted into proteoliposomes and used to raise high-affinity antibodies. We have developed a strategy to discover antibodies that are useful for structural studies. A straightforward approach for the expression of antibody fragments in Sf9 cells has also been established. Transporter-antibody complexes purified using this procedure are well-behaved and readily crystallize, producing complexes with S-citalopram that diffract X-rays to 3-4 &#197; resolution. The strategies developed here can be utilized to determine the structure of other challenging membrane proteins.

Thermostabilization, Expression, Purification, and Crystallization of the Human Serotonin Transporter Bound to S-citalopram

This manuscript describes how to screen for thermostabilizing mutations, purify the human serotonin transporter, generate high affinity antibodies, and crystallize the serotonin transporter-antibody complex bound to the antidepressant drug S-citalopram. This protocol can be adapted to the study of other challenging membrane transporters, receptors, and channels.

Termoestabilização, expressão, purificação e cristalização do transportador de serotonina humano Bound to<em&gt; S</em&gt; -citalopram

The serotonin transporter is a sodium and chloride-coupled transporter that &#34;pumps&#34; extracellular serotonin into cells. S-citalopram is a drug ...

Bioquímica

Expression and Purification of Mammalian Bestrophin Ion Channels

The human genome encodes four bestrophin paralogs, namely BEST1, BEST2, BEST3, and BEST4. BEST1, encoded by the BEST1 gene, is a Ca2+-activated Cl- channel (CaCC) predominantly expressed in retinal pigment epithelium (RPE). The physiological and pathological significance of BEST1 is highlighted by the fact that over 200 distinct mutations in the BEST1 gene have been genetically linked to a spectrum of at least five retinal degenerative disorders, such as Best vitelliform macular dystrophy (Best disease). Therefore, understanding the biophysics of bestrophin channels at the single-molecule level holds tremendous significance. However, obtaining purified mammalian ion channels is often a challenging task. Here, we report a protocol for the expression of mammalian bestrophin proteins with the BacMam baculovirus gene transfer system and their purification by affinity and size-exclusion chromatography. The purified proteins have the potential to be utilized in subsequent functional and structural analyses, such as electrophysiological recording in lipid bilayers and crystallography. Importantly, this pipeline can be adapted to study the functions and structures of other ion channels.

The purification of ion channels is often challenging, but once achieved, it can potentially allow in vitro investigations of the functions and structures of the channels. Here, we describe the stepwise procedures for the expression and purification of mammalian bestrophin proteins, a family of Ca2+-activated Cl- channels.

Expressão e purificação dos canais de íon Bestrophin mamíferos

The human genome encodes four bestrophin paralogs, namely BEST1, BEST2, BEST3, and BEST4. BEST1, encoded by the BEST1 gene, is a Ca2+-activated Cl- ...

Caffeine Extraction, Enzymatic Activity and Gene Expression of Caffeine Synthase from Plant Cell Suspensions

Caffeine (1,3,7-trimethylxanthine) is a purine alkaloid present in popular drinks such as coffee and tea. This secondary metabolite is regarded as a chemical defense because it has antimicrobial activity and is considered a natural insecticide. Caffeine can also produce negative allelopathic effects that prevent the growth of surrounding plants. In addition, people around the world consume caffeine for its analgesic and stimulatory effects. Due to interest in the technological applications of caffeine, research on the biosynthetic pathway of this compound has grown. These studies have primarily focused on understanding the biochemical and molecular mechanisms that regulate the biosynthesis of caffeine. In vitro tissue culture has become a useful system for studying this biosynthetic pathway. This article will describe a step-by-step protocol for the quantification of caffeine and for measuring the transcript levels of the gene (CCS1) encoding caffeine synthase (CS) in cell suspensions of C. arabica L. as well as its activity.

This protocol describes an efficient methodology for the extraction and quantification of caffeine in cell suspensions of C. arabica L. and an experimental process for evaluating the enzymatic activity of caffeine synthase with the expression level of the gene that encodes this enzyme.

Extração de cafeína, atividade enzimática e expressão gênica de cafeína sintase de suspensões celulares de planta

Caffeine (1,3,7-trimethylxanthine) is a purine alkaloid present in popular drinks such as coffee and tea. This secondary metabolite is regarded as a ...

Anaerobic Protein Purification and Kinetic Analysis via Oxygen Electrode for Studying DesB Dioxygenase Activity and Inhibition

Oxygen-sensitive proteins, including those enzymes which utilize oxygen as a substrate, can have reduced stability when purified using traditional aerobic purification methods. This manuscript illustrates the technical details involved in the anaerobic purification process, including the preparation of buffers and reagents, the methods for column chromatography in a glove box, and the desalting of the protein prior to kinetics. Also described are the methods for preparing and using an oxygen electrode to perform kinetic characterization of an oxygen-utilizing enzyme. These methods are illustrated using the dioxygenase enzyme DesB, a gallate dioxygenase from the bacterium Sphingobium sp. strain SYK-6.

Here we present a protocol for anaerobic protein purification, anaerobic protein concentration, and subsequent kinetic characterization using an oxygen electrode system. The method is illustrated using the enzyme DesB, a dioxygenase enzyme which is more stable and active when purified and stored in an anaerobic environment.

Purificação de proteínas anaeróbica e análise cinética através do eletrodo de oxigênio para estudar a inibição e atividade dioxigenase DesB

Oxygen-sensitive proteins, including those enzymes which utilize oxygen as a substrate, can have reduced stability when purified using traditional aerobic ...

Expression and Purification of the Human Lipid-sensitive Cation Channel TRPC3 for Structural Determination by Single-particle Cryo-electron Microscopy

Transient receptor potential channels (TRPCs) of the canonical TRP subfamily are nonselective cation channels that play an essential role in calcium homeostasis, particularly store-operated calcium entry, which is critical to maintaining proper function of synaptic vesicle release and intracellular signaling pathways. Accordingly, TRPC channels have been implicated in a variety of human diseases including cardiovascular disorders such as cardiac hypertrophy, neurodegenerative disorders such as Parkinson&#39;s disease, and neurologic disorders such as spinocerebellar ataxia. Therefore, TRPC channels represent a potential pharmacologic target in human diseases. However, the molecular mechanisms of gating in these channels are still unclear. The difficulty in obtaining large quantities of stable, homogeneous, and purified protein has been a limiting factor in structure determination studies, particularly for mammalian membrane proteins such as the TRPC ion channels. Here, we present a protocol for the large-scale expression of mammalian ion channel membrane proteins using a modified baculovirus gene transfer system and the purification of these proteins by affinity and size-exclusion chromatography. We further present a protocol to collect single-particle cryo-electron microscopy images from purified protein and to use these images to determine the protein structure. Structure determination is a powerful method for understanding the mechanisms of gating and function in ion channels.

This protocol describes techniques used to determine ion channel structures by cryo-electron microscopy, including a baculovirus system used to efficiently express genes in mammalian cells with minimum effort and toxicity, protein extraction, purification, and quality checking, sample grid preparation and screening, as well as data collection and processing.

Expressão e purificação de TRPC3 os humanos sensíveis lipídico cação canal para determinação estrutural por microscopia de Single-particle Cryo-elétron

Transient receptor potential channels (TRPCs) of the canonical TRP subfamily are nonselective cation channels that play an essential role in calcium ...

Expression, Solubilization, and Purification of Eukaryotic Borate Transporters

The Solute Carrier 4 (SLC4) family of proteins is called the bicarbonate transporters and includes the archetypal protein Anion Exchanger 1 (AE1, also known as Band 3), the most abundant membrane protein in the red blood cells. The SLC4 family is homologous with borate transporters, which have been characterized in plants and fungi. It remains a significant technical challenge to express and purify membrane transport proteins to homogeneity in quantities suitable for&#160;structural or functional studies. Here we describe detailed procedures for the overexpression of borate transporters in Saccharomyces cerevisiae, isolation of yeast membranes, solubilization of protein by detergent, and purification of borate transporter homologs from S. cerevisiae, Arabidopsis thaliana, and Oryza sativa. We also detail a glutaraldehyde cross-linking experiment to assay multimerization of homomeric transporters. Our generalized procedures can be applied to all three proteins and have been optimized for efficacy. Many of the strategies developed here can be utilized for the study of other challenging membrane proteins.

Here we present a protocol to express, solubilize, and purify several eukaryotic borate transporters with homology to the SLC4 transporter family using yeast. We also describe a chemical cross-linking assay to assess the purified homomeric proteins for multimeric assembly. These protocols can be adapted for other challenging membrane proteins.

Expressão, solubilização e purificação de transportadores eucarióticas borato

The Solute Carrier 4 (SLC4) family of proteins is called the bicarbonate transporters and includes the archetypal protein Anion Exchanger 1 (AE1, also ...

Expression and Purification of Nuclease-Free Oxygen Scavenger Protocatechuate 3,4-Dioxygenase

Single molecule (SM) microscopy is used in the study of dynamic molecular interactions of fluorophore labeled biomolecules in real time. However, fluorophores are prone to loss of signal via photobleaching by dissolved oxygen (O2). To prevent photobleaching and extend the fluorophore lifetime, oxygen scavenging systems (OSS) are employed to reduce O2. Commercially available OSS may be contaminated by nucleases that damage or degrade nucleic acids, confounding interpretation of experimental results. Here we detail a protocol for the expression and purification of highly active Pseudomonas putida protocatechuate-3,4-dioxygenase (PCD) with no detectable nuclease contamination. PCD can efficiently remove reactive O2 species by conversion of the substrate protocatechuic acid (PCA) to 3-carboxy-cis,cis-muconic acid. This method can be used in any aqueous system where O2 plays a detrimental role in data acquisition. This method is effective in producing highly active, nuclease free PCD in comparison with commercially available PCD.

Protocatechuate 3,4-dioxygenase (PCD) can enzymatically remove free diatomic oxygen from an aqueous system using its substrate protocatechuic acid (PCA). This protocol describes the expression, purification, and activity analysis of this oxygen scavenging enzyme.

Expressão e purificação do protocatechuato de oxigênio sem nuclease 3,4-Dioxigenase

Single molecule (SM) microscopy is used in the study of dynamic molecular interactions of fluorophore labeled biomolecules in real time. However, ...

Expression, Purification, Crystallization, and Enzyme Assays of Fumarylacetoacetate Hydrolase Domain-Containing Proteins

Fumarylacetoacetate hydrolase (FAH) domain-containing proteins (FAHD) are identified members of the FAH superfamily in eukaryotes. Enzymes of this superfamily generally display multi-functionality, involving mainly hydrolase and decarboxylase mechanisms. This article presents a series of consecutive methods for the expression and purification of FAHD proteins, mainly FAHD protein 1 (FAHD1) orthologues among species (human, mouse, nematodes, plants, etc.). Covered methods are protein expression in E. coli, affinity chromatography, ion exchange chromatography, preparative and analytical gel filtration, crystallization, X-ray diffraction, and photometric assays. Concentrated protein of high levels of purity (&#62;98%) may be employed for crystallization or antibody production. Proteins of similar or lower quality may be employed in enzyme assays or used as antigens in detection systems (Western-Blot, ELISA). In the discussion of this work, the identified enzymatic mechanisms of FAHD1 are outlined to describe its hydrolase and decarboxylase bi-functionality in more detail.

Expression and purification of fumarylacetoacetate hydrolase domain-containing proteins is described with examples (expression in E. coli, FPLC). Purified proteins are used for crystallization and antibody production and employed for enzyme assays. Selected photometric assays are presented to display the multi-functionality of FAHD1 as oxaloacetate decarboxylase and acylpyruvate hydrolase.

Expressão, purificação, cristalização e ensaios enzimáticos de proteínas contendo domínio de Fumarilacetoacetato de hidrolase

Fumarylacetoacetate hydrolase (FAH) domain-containing proteins (FAHD) are identified members of the FAH superfamily in eukaryotes. Enzymes of this ...

PCR Mutagenesis, Cloning, Expression, Fast Protein Purification Protocols and Crystallization of the Wild Type and Mutant Forms of Tryptophan Synthase

Structural studies with tryptophan synthase (TS) bienzyme complex (&#945;2&#946;2 TS) from Salmonella typhimurium have been performed to better understand its catalytic mechanism, allosteric behavior, and details of the enzymatic transformation of substrate to product in PLP-dependent enzymes. In this work, a novel expression system to produce the isolated &#945;- and isolated &#946;-subunit allowed the purification of high amounts of pure subunits and &#945;2&#946;2 StTS complex from the isolated subunits within 2 days. Purification was carried out by affinity chromatography followed by cleavage of the affinity tag, ammonium sulfate precipitation, and size exclusion chromatography (SEC). To better understand the role of key residues at the enzyme &#946;-site, site-direct mutagenesis was performed in prior structural studies. Another protocol was created to purify the wild type and mutant &#945;2&#946;2 StTS complexes. A simple, fast and efficient protocol using ammonium sulfate fractionation and SEC allowed purification of &#945;2&#946;2 StTS complex in a single day. Both purification protocols described in this work have considerable advantages when compared with previous protocols to purify the same complex using PEG 8000 and spermine to crystalize the &#945;2&#946;2 StTS complex along the purification protocol. Crystallization of wild type and some mutant forms occurs under slightly different conditions, impairing the purification of some mutants using PEG 8000 and spermine. To prepare crystals suitable for x-ray crystallographic studies several efforts were made to optimize crystallization, crystal quality and cryoprotection. The methods presented here should be generally applicable for purification of tryptophan synthase subunits and wild type and mutant &#945;2&#946;2 StTS complexes.

This article presents a series of consecutive methods for the expression and purification of Salmonella typhimurium tryptophan synthase comp this protocol a rapid system to purify the protein complex in a day. Covered methods are site-directed mutagenesis, protein expression in Escherichia coli, affinity chromatography, gel filtration chromatography, and crystallization.

PCR Mutagenesis, Clonagem, Expressão, Protocolos rápidos de purificação de proteínas e Cristalização do Tipo Selvagem e Formas Mutantes de Synthase Triptofano

Structural studies with tryptophan synthase (TS) bienzyme complex (&#945;2&#946;2 TS) from Salmonella typhimurium have been performed to better understand ...

Ganglioside Extraction, Purification and Profiling

Gangliosides are glycosphingolipids that contain one or more sialic acid residues. They are found on all vertebrate cells and tissues but are especially abundant in the brain. Expressed primarily on the outer leaflet of the plasma membranes of cells, they modulate the activities of cell surface proteins via lateral association, act as receptors in cell-cell interactions and are targets for pathogens and toxins. Genetic dysregulation of ganglioside biosynthesis in humans results in severe congenital nervous system disorders. Because of their amphipathic nature, extraction, purification, and analysis of gangliosides require techniques that have been optimized by many investigators in the 80 years since their discovery. Here, we describe bench-level methods for the extraction, purification, and preliminary qualitative and quantitative analyses of major gangliosides from tissues and cells that can be completed in a few hours. We also describe methods for larger scale isolation and purification of major ganglioside species from brain. Together, these methods provide analytical and preparative scale access to this class of bioactive molecules.

Gangliosides are sialic acid-bearing glycosphingolipids that are particularly abundant in the brain. Their amphipathic nature requires organic/aqueous extraction and purification techniques to ensure optimal recovery and accurate analyses. This article provides overviews of analytic and preparative scale ganglioside extraction, purification, and thin layer chromatography analysis.

Extração de ganglioside, purificação e perfil

Gangliosides are glycosphingolipids that contain one or more sialic acid residues. They are found on all vertebrate cells and tissues but are especially ...