RESUMO
Deep Eutectic Solvents (DES) were investigated as new reaction media for the synthesis of alkyl glycosides catalyzed by the thermostable α-amylase from Thermotoga maritima Amy A. The enzyme was almost completely deactivated when assayed in a series of pure DES, but as cosolvents, DES containing alcohols, sugars, and amides as hydrogen-bond donors (HBD) performed best. A choline chloride:urea based DES was further characterized for the alcoholysis reaction using methanol as a nucleophile. As a cosolvent, this DES increased the hydrolytic and alcoholytic activity of the enzyme at low methanol concentrations, even when both activities drastically dropped when methanol concentration was increased. To explain this phenomenon, variable-temperature, circular dichroism characterization of the protein was conducted, finding that above 60 °C, Amy A underwent large conformational changes not observed in aqueous medium. Thus, 60 °C was set as the temperature limit to carry out alcoholysis reactions. Higher DES contents at this temperature had a detrimental but differential effect on hydrolysis and alcoholysis reactions, thus increasing the alcoholyisis/hydrolysis ratio. To the best of our knowledge, this is the first report on the effect of DES and temperature on an enzyme in which structural studies made it possible to establish the temperature limit for a thermostable enzyme in DES.
Assuntos
Proteínas de Bactérias/metabolismo , Glicosídeos/metabolismo , Solventes/química , Thermotoga maritima/enzimologia , alfa-Amilases/metabolismo , Proteínas de Bactérias/química , Biocatálise , Colina/química , Dicroísmo Circular , Estabilidade Enzimática , Temperatura Alta , Ligação de Hidrogênio , Hidrólise , Metanol/química , Conformação Proteica , Ureia/química , alfa-Amilases/químicaRESUMO
Isolating endogenous SUMOylated proteins is a challenging task due to the high reversibility of this posttranslational modification. We have shown that SUMO traps are useful tools for the enrichment and isolation of proteins modified by SUMO in vitro and in vivo. To characterize the affinity and specificity of different SUMO chains for these traps, that are based on SUMO-interacting motifs, we have used real-time surface plasmon resonance (SPR), which allows a label-free analysis of protein/protein interactions. Here, a protocol to determine the affinities of multivalent SUMO traps for polySUMO chains or mono-SUMO molecules by SPR is presented.
Assuntos
Processamento de Proteína Pós-Traducional , Proteína SUMO-1/metabolismo , Proteínas Modificadoras Pequenas Relacionadas à Ubiquitina/metabolismo , Ressonância de Plasmônio de Superfície/métodos , Anticorpos/química , Clonagem Molecular , Escherichia coli/genética , Escherichia coli/metabolismo , Expressão Gênica , Vetores Genéticos/química , Vetores Genéticos/metabolismo , Glutationa Transferase/genética , Glutationa Transferase/metabolismo , Humanos , Procedimentos Analíticos em Microchip , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Proteína SUMO-1/genética , Proteínas Modificadoras Pequenas Relacionadas à Ubiquitina/genética , SumoilaçãoRESUMO
A Mycobacterium tuberculosis culture filtrate enriched with mannose-containing proteins was resolved by 2-DE gel. After ConA ligand blotting, 41 proteins were identified by mass spectrometry as putative glycoproteins with 34 of them new probably mannosylated proteins. These results contribute to the construction of the ConA affinity glycoprotein database of M. tuberculosis, and provide useful information for understanding the biological role of glycoproteins in mycobacteria.