Enzyme Mechanisms in Temperature and Pressure Adaptation of Off-Shore Benthic Organisms: The Basic Problem

Abstract

SYNOPSIS: The degree of participation of any given enzyme reaction in metabolism is not determined by energy-volume relationships, but rather by enzyme affinities for key regulatory ligands. In temperature adaptation, enzyme-substrate affinities often decrease as thermal kinetic energy increases, thus compensating for temperature-induced changes in reaction velocity at low substrate concentrations. Since the effects of pressure are not unidirectional (some enzymes are accelerated; some are unaffected; some are decelerated), a more functional solution in pressure adaptation is to elaborate enzymes whose affinities for key metabolites are pressure independent. In consequence, at physiological substrate concentrations, the pressure sensitivities of catalysis and control of catalysis are probably held at a minimum.