Effects of Hydrostatic Pressure on Catalysis by Epaxial Muscle Phosphofructokinase from an Abyssal Fish

Abstract

SYNOPSIS: Phosphofructokinase (PFK) extracted from muscle of abyssal Coryphaenoides fishes common in the deep waters around the Galápagos Archipelago is extremely unstable upon decompression and extraction and can be recovered only in low activities. Preliminary studies indicate that the pressure responses of the enzyme are complex: At low pressures, the enzyme is activated; at moderate pressures, activity passes through a pressure optimum; at high pressures, maximum catalytic activity is decelerated. At low pressures, the volume change of activation is about −11 cm³/mole at 3°C and increases to about −46 cm³/mole at 28°C. The homologous enzyme from a surface species (Oligoplites mundus) appears to be more pressure sensitive at low temperatures.