The specificity of alpha-glucosidase from Saccharomyces cerevisiae differs depending on the type of reaction: hydrolysis versus transglucosylation
Authorized Users Only
Segal, Ann Marie
Šegan, Dejan M.
Article (Published version)
MetadataShow full item record
Our investigation of the catalytic properties of Saccharomyces cerevisiae alpha-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 a-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.
Keywords:Aglycon specificity / alpha-glucosidase / Transglucosylation kinetics / Hydrolysis kinetics / Substrate inhibition / Hydroxybenzyl alcohol
Source:Applied Microbiology and Biotechnology, 2014, 98, 14, 6317-6328
- Springer, New York
- Allergens, antibodies, enzymes and small physiologically important molecules: design, structure, function and relevance (RS-172049)
- Novel encapsulation and enzyme technologies for designing of new biocatalysts and biologically active compounds targeting enhancement of food quality, safety and competitiveness (RS-46010)
- Reinforcement of the Faculty of Chemistry, University of Belgrade, towards becoming a Center of Excellence in the region of WB for Molecular Biotechnology and Food research (EU-256716)