Abstract
1. During denaturation of DFP-inhibited BPN' in 0.01M phosphate solution, the order of the reaction changes from first to zero on lowering the pH below 4.5 and on raising the pH above 10.5 at 56°C. A zero-order reaction was observed on acid denaturation in acetate solution.
2. The acid and alkali denaturation of BPN' and DFP-inhibited BPN' where first-order reactions were found indicated a typical acid-base catalysis.
3. During acid and alkali denaturations the effect of ionic strength on BPN' and DFP-inhibited BPN', where first-order reac-
tions were seen, indicated reactions between ions of the same signs.
4. A measurement of thermodynamic parameters of BPN' and DFP-inhibited BPN' showed that the difference in the rate con-stant during acid and alkali denaturation is mainly due to differences in the entropies of activation.
The author wishes to express his sincere thanks to Prof. K. Okunuki for his continuous encourage-ment and interest during the course of this work and also to Nagase Company for kindly supplying the crystalline bacterial proteinase, “Nagarse”.
