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Why substrate depletion has apparent first-order kinetics in enzymatic digestion

Paper ID Volume ID Publish Year Pages File Format Full-Text
15465 1415 2006 6 PDF Available
Title
Why substrate depletion has apparent first-order kinetics in enzymatic digestion
Abstract

A number of enzyme digestion assays show apparent first-order kinetics of reactant depletion. There are four possible explanations of this phenomenon: (i) the reaction is dominated by a first-order limiting step, (ii) the digestion follows a pseudo-first-order kinetics under the excess of a reactant species, (iii) the first-order kinetics is only applicable to the slow transient of the reaction, or (iv) the aggregate behavior of the reaction pathway produces behavior indistinguishable from the first-order kinetics. In this paper, we investigate the kinetics for protein digestion by formulating rate equations for two proposed mechanisms, namely the one-by-one mechanism and the zipper mechanism. Our analysis shows that the kinetics of protein digestion follows apparent first-order kinetics irrespective of the mechanism for low initial substrate concentration compared to the initial enzyme concentration. Also, our results provide an explanation for experimental observations and suggest a new experimental protocol that could reveal information on the mechanism of digestion.

Keywords
Apparent first-order behavior; Enzyme digestion; One-by-one mechanism; Zipper mechanism; Mechanism distinguishability
First Page Preview
Why substrate depletion has apparent first-order kinetics in enzymatic digestion
Publisher
Database: Elsevier - ScienceDirect
Journal: Computational Biology and Chemistry - Volume 30, Issue 3, June 2006, Pages 209–214
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering