A Two-Step Model that Predicts α-Amylase Activity in Solvents with High and Low Dielectric Constants
Journal Title: Biomedical Journal of Scientific & Technical Research (BJSTR) - Year 2019, Vol 19, Issue 1
Abstract
Some years ago, the present author put forward a two-step inactivation model for α-amylase (enzyme). The effect of heat and various substances on the enzyme activity have already been studied experimentally in aqueous solutions and confirmed the theoretical predictions of the model. In this paper we describe the effect of solvents with varied dielectric constants on the enzyme activity.α-Amylase is a metallo-enzyme that contains at least 1mol of calcium ion [1-4] per mole of protein. The strength of the binding of calcium ions to the protein varies according to the source of the enzyme, and for all α-amylases the presence of calcium ions increases the stability of the enzyme toward denaturation by heat, acid, or urea [2]. Irrespective of the source, this enzyme causes a rapid fragmentation of starch molecules into sugars [5-7] and undergoes inactivation reaction initiated by an initial dissociation of Ca2+ ions followed by denaturation by heat [8-10].The first reversible stage (eq 1) involves a forward reaction that forms an inactive apoenzyme, E2-, from the active enzyme, CaE, with a rate constant of k1 and a reverse reactivation reaction involving the combination of E2- with calcium ions with a rate constant of k-1. The second irreversible stage (eq 2) of reaction forms a denatured form of the enzyme, EI2-, from E2- with a rate constant of k2 . The reversibly inactivated form, E2-, can be quickly transformed into the active form, CaE, by adding calcium ions. On the other hand, the EI2- is the denatured form of the enzyme that cannot be reactivated by adding calcium ions.
Authors and Affiliations
Arshad Khan
Keywords
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- EP ID EP622400
- DOI 10.26717/BJSTR.2019.19.003251
- Views 138
- Downloads 0
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