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KINETICS OF THE INTERACTION OF PANCREATIC α‐AMYLASE WITH A KIDNEY BEAN ( PHASEOLUS VULGARIS ) ‐ AMYLASE INHIBITOR
Author(s) -
TANIZAKI MARTHA MASSAKO,
LAJOLO FRANCO M.
Publication year - 1985
Publication title -
journal of food biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 47
eISSN - 1745-4514
pISSN - 0145-8884
DOI - 10.1111/j.1745-4514.1985.tb00340.x
Subject(s) - phaseolus , amylase , chemistry , kinetics , enzyme , dissociation constant , reaction rate constant , dissociation (chemistry) , nuclear chemistry , chromatography , biochemistry , organic chemistry , biology , botany , receptor , physics , quantum mechanics
An amylase inhibitor isolated from black beans (Phaseolus vulgaris) can completely inhibit porcine pancreatic α‐amylase forming a 1:1 stoichiometric complex . The kinetic pattern of complex formation is pH dependent. At pH 5.5 it follows a first order reaction with rate constant of 0.029 min −1 and 0.017 min −1 at 37°C and equimolar inhibitor and enzyme concentration, respectively, of 10 −8 M and 10 −9 M. At pH 6.9 it is a second order reaction, with a rate constant of 0.25 × 10 6 M −1 min −1 at 37°C, with 4 × 10 −8 M concentrations of enzyme and inhibitor. The dissociation constants of the enzymeinhibitor complex are 1.7 × 10 −10 M at pH 5.5 and 4.4 × 10 −9 M at pH 6.9, at 37°C. The kinetic data obtained at pH 5.5 suggested the formation of an initial reversible complex followed by a conformational change step. The complex can be dissociated either in acid pH (4.3) or at pH values higher than 6, 5 with partial recovery of the amylase activity.