The life span of steps in the enzyme-catalyzed reaction, its implications, and matters of general interest

Author:

Udema Ikechukwu IlohORCID

Abstract

ABSTRACTThere is increasing recognition for steps and their life span (LS) in the enzyme-catalyzed reaction pathway; the need for rate constants, activation parameters, and transition states (TS) has assumed preeminence in the literature. The determination of the life span of complexes, enzyme-product (EP) complexes in particular, is not a regular feature in most studies. The study aims to show that there is LS for EP and TS destined for irreversible product formation and release. The cognate objectives are to: 1) derive the equation for the graphical determination of the first-order rate constant (FORC) of EP dissociation into E and P as well as the FORC of ES dissociation to free enzyme, E, and free substrate, S; 2) derive a FORC equation for the TS to EP conversion; 3) calculate the duration; and 4) calculate the FORC for the TS to EP conversion. Using mesophilic alpha-amylase and the Bernfeld method of assay, the velocities of catalysis were used to generate first the Michaelian parameters and then the rate constants. The LS of the TS and the FORC for the conversion of the enzyme-substrate (ES) complex to TS are 4.321 exp. (−6) min and 2.314 exp. (+5)/min, respectively; the LS of the TS destined for backward conversion (deactivation) to ES and its FORC are 7.525 exp. (−7) min and 1.387 exp. (+6)/min, respectively; the LS of the EP and its FORC for dissociation to E and P are 1.33 exp. (−5) and 7.52 exp. (+4)/min respectively. In conclusion, there are always steps in an enzyme-catalyzed reaction in the catalytic cycle; the LS of each step is shorter than the total LS of deactivation and dissociation processes; this is applicable to forward reactions. Thermodynamic activation parameters must account for all FORC in accordance with the additivity principle.

Publisher

Cold Spring Harbor Laboratory

同舟云学术

1.学者识别学者识别

2.学术分析学术分析

3.人才评估人才评估

"同舟云学术"是以全球学者为主线,采集、加工和组织学术论文而形成的新型学术文献查询和分析系统,可以对全球学者进行文献检索和人才价值评估。用户可以通过关注某些学科领域的顶尖人物而持续追踪该领域的学科进展和研究前沿。经过近期的数据扩容,当前同舟云学术共收录了国内外主流学术期刊6万余种,收集的期刊论文及会议论文总量共计约1.5亿篇,并以每天添加12000余篇中外论文的速度递增。我们也可以为用户提供个性化、定制化的学者数据。欢迎来电咨询!咨询电话:010-8811{复制后删除}0370

www.globalauthorid.com

TOP

Copyright © 2019-2024 北京同舟云网络信息技术有限公司
京公网安备11010802033243号  京ICP备18003416号-3