Ralston I M, Wauters J, Heremans K, Dunford H B
Biophys Chem. 1982 Apr;15(1):15-8. doi: 10.1016/0301-4622(82)87012-9.
The activation volumes for the reactions of horseradish peroxidase compound II with L-tyrosine, 3-iodo-L-tyrosine, p-aminobenzoic acid and ferrocyanide were determined by using a high-pressure stopped-flow technique at 25 degrees C and pH 7. For the tyrosines, the solvent electrostriction accompanying substrate ionization and H+ transfer from the substituted phenol to a basic group of the enzyme can account for the observed negative activation volumes. For p-aminobenzoic acid a simple electron transfer without H+ transfer appears to occur. The positive activation volume for ferrocyanide may be explained in terms of electron transfer associated with a large change in electrostriction of the inorganic redox couple.
