JBC, Vol. 253, Issue 6, 1947-1953, Mar, 1978
Pressure effects on folded proteins in solution. Hydrogen exchange at elevated pressures
J. V. Carter, D. G. Knox and A. Rosenberg
The observed rate constants for base-catalyzed hydrogen exchange reactions
between solvent water and peptide nitrogen in lysozyme, ribonculease A,
oxidized ribonuclease A, and poly(DL-lysine) are all enhanced by an
increase in pressure. Activation volumes have been calculated from the
pressure effect on these rate constants. For the folded proteins lysozyme
and ribonuclease A, deltaV for base-catalyzed exchange changes from about
+9 ml/mol at atmospheric pressure -3 ml/mol at 2500 kg/cm2. The same
quantity, determined for the random coil polypeptides oxidized ribonuclease
A and poly(DL-lysine), does not show this dependence upon pressure. These
effects can be understood either in terms of solvent penetration on the
folded proteins or the onset of a small degree of pressure induced
unfolding. Possible mechanisms by which such penetration could occur are
discussed.