The catalytic activities of monomeric enzymes show complex pressure dependence.
High hydrostatic pressures in the biologically relevant range (< or = 1,200 bar) are known to cause dissociation of oligomeric enzymes in vitro, whereas protein denaturation requires pressures far beyond this range. Pressure-induced inactivation phenomena attributable to neither of these effects are shown to occur in monomeric enzymes. Three different types of pressure dependence can be distinguished: (1) a linear dependence of catalytic rate constants on pressure, as predicted by the activated complex theory, observed for lysozyme and thermolysin; (2) a biphasic profile consisting of two linear contributions, found for trypsin; (3) maximum curves, as observed for both directions of the octopine dehydrogenase reaction. The third case may be ascribed to a pressure-induced decrease in the partial specific volume of the protein, resulting in reduced flexibility of the active site. This mechanism may also apply to the pressure-induced inactivation of assembly systems stabilized against dissociation in the cell.
Gross
M
M
Institut für Biophysik und physikalische Biochemie, Universität Regensburg, Germany.
Auerbach
G
G
Jaenicke
R
R
D000594:Amino Acid Oxidoreductases / Q000378:metabolism*; D000818:Animals; D002384:Catalysis; D004798:Enzymes / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D008974:Mollusca; D009113:Muramidase / Q000378:metabolism*; D011312:Pressure; D013820:Thermolysin / Q000378:metabolism*; D014357:Trypsin / Q000378:metabolism*
D004798:Enzymes; D000594:Amino Acid Oxidoreductases; C021903:D-octopine dehydrogenase; D009113:Muramidase; D014357:Trypsin; D013820:Thermolysin