期刊
BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
卷 319, 期 4, 页码 1265-1271出版社
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.bbrc.2004.05.122
关键词
human salivary alpha-amylase; tannin; gallotannin; quinic acid; inhibition; mixed non-competitive
Here, we first report on the effectiveness and specificity of tannin inhibition of 2-chloro-4-nitrophenyl-4-O-beta-D-galactopyranosylmaltoside hydrolysis that is catalyzed by human salivary alpha-amylase (HSA). Tannin was gallotannin in which quinic acid was esterified with 2-7 units of gallic acid. A number of studies establish that polyphenols-like tannins-may prevent oral diseases, e.g., dental caries. Kinetic analyses confirmed that the inhibition of hydrolysis is a mixed non-competitive type and only one molecule of tannin binds to the active site or the secondary site of the enzyme. Since Dixon plots were linear, product formation could be excluded from the enzyme-substrate-inhibitor complex (ESI). Kinetic constants calculated from secondary plots and non-linear regression are almost identical, thereby confirming the suggested model. Kinetic constants (K-EI = 9.03 mug mL(-1), K-ESI = 47.84 mug mL(-1)) show that tannin is as an effective inhibitor of HSA as acarbose and indicate a higher stability for the enzyme-inhibitor complex than ESI. (C) 2004 Published by Elsevier Inc.
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