Year: 1974
Type: article
Abstract: A general approach to elucidating the molecular basis of enzyme catalysis and regulation is the time resolution of the complex reaction mechanisms involved into their elementary steps.Both enzyme catalysis and enzyme regulation are initiated by the binding of small molecules to the protein.This association reaction is generally quite rapid and is often followed by a conformational change of the macromolecule.These conformational changes are discussed in terms of the dynamics of the underlying elementary processes, hydrogen bonding, solvation and hydrophobic interactions, all ofwhich have been studied in model systems.Enzyme catalysis often involves acid-base catalysis.Consideration of the rates of both concerted and sequential proton transfer mechanisms in terms of model systems suggests that the observed turnover numbers of enzymes require that proton transfer steps in the catalytic process occur at close to their maximum possible rates.A generat mechanism for enzyme catalysis is proposed and is illustrated by the mechanism of action of ribonuclease A. A distinguishing feature of most regulatory enzymes is their multi-subunit nature.The regulation of enzyme activity usually is achieved by alteration of subunit interactions through conformational changes triggered by Iigand binding.These conformational transitions are important processes in the cooperative binding of substrates and effectors to regulatory enzymes.As an example, the mechanism of the regulation of aspartate transcarbamylase from Escherichia coli is considered: in this case coupled conformational changes appear to be utilized as interlocking on-off switches for the enzymic activity.
Source: Pure and Applied Chemistry
Author: G. G. Hammes
Institution: Cornell University
Language: English
Topic: Chemical Reaction Mechanisms
Subfield: Organic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W1983509225