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

SYNOPSIS: Phosphofructokinase (PFK) extracted from muscle ofabyssal Coryphaenoides fishes common in the deep waters aroundthe Galápagos Archipelago is extremely unstable upondecompression and extraction and can be recovered only in lowactivities. Preliminary studies indicate that the pressure responsesof 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 –11cm³/mole at 3°C and increases to about –46 cm³/moleat 28°C. The homologous enzyme from a surface species (Oligoplitesmundus) appears to be more pressure sensitive at low temperatures.