specificity of α-glucosidase from Saccharomyces cerevisiae differs depending on the type of reaction: hydrolysis versus transglucosylation

Our investigation of the catalytic properties of Saccharomyces cerevisiae α-glucosidase (AGL) using hydroxybenzyl alcohol (HBA) isomers as transglucosylation substrates and their glucosides in hydrolytic reactions demonstrated interesting findings pertaining to the aglycon specificity of this import...

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Bibliographic Details
Published in:Applied microbiology and biotechnology 2014, Vol.98 (14), p.6317-6328
Main Authors: Dušan, Veličković, Nenad, Milosavić, Dejan, Bezbradica, Filip, Bihelović, Segal, Ann Marie, Dejan, egan, Jovana, Trbojević, Aleksandra, Dimitrijević
Format: Article
Language:English
Subjects:
alcohols
alpha-glucosidase
alpha-Glucosidases - chemistry
alpha-Glucosidases - metabolism
Biomedical and Life Sciences
Biotechnologically Relevant Enzymes and Proteins
Biotechnology
Brewer's yeast
Genetic aspects
glucosides
Hydrolysis
isomers
Kinetics
Life Sciences
Microbial Genetics and Genomics
Microbiology
Physiological aspects
Saccharomyces cerevisiae
Saccharomyces cerevisiae - enzymology
Substrate Specificity
Transferases
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Summary:Our investigation of the catalytic properties of Saccharomyces cerevisiae α-glucosidase (AGL) using hydroxybenzyl alcohol (HBA) isomers as transglucosylation substrates and their glucosides in hydrolytic reactions demonstrated interesting findings pertaining to the aglycon specificity of this important enzyme. AGL specificity increased from the para(p)- to the ortho(o)-HBA isomer in transglucosylation, whereas such AGL aglycon specificity was not seen in hydrolysis, thus indicating that the second step of the reaction (i.e., binding of the glucosyl acceptor) is rate-determining. To study the influence of substitution pattern on AGL kinetics, we compared AGL specificity, inferred from kinetic constants, for HBA isomers and other aglycon substrates. The demonstrated inhibitory effects of HBA isomers and their corresponding glucosides on AGL-catalyzed hydrolysis of p-nitrophenyl α-glucoside (PNPG) suggest that HBA glucosides act as competitive, whereas HBA isomers are noncompetitive, inhibitors. As such, we postulate that aromatic moieties cannot bind to an active site unless an enzyme-glucosyl complex has already formed, but they can interact with other regions of the enzyme molecule resulting in inhibition.
ISSN:0175-7598
1432-0614
DOI:10.1007/s00253-014-5587-9