Relaxation kinetics of glutamate dehydrogenase self-association by pressure perturbation.

The kinetics of self-association for beef liver glutamate dehydrogenase (EC 1.4.1.3) have been measured by using pressure perturbation in both the time domain and the frequency domain by monitoring scattered light intensity. The kinetic behavior is entirely consistent with the random self-association model proposed by Thusius et al. [Thusius, D., Dessen, P., & Jallon, J. M. (1975) J. Mol. Biol. 92, 413--432]. The activation volume deltaV for association is estimated to be positive, and it is shown that this provides further corroboration of the molecular mechanism advanced by these same authors. A rapid shift in scattered light intensity is attributed to preferential interaction between the phosphate anion and the protein, proceeding with a positive volume change (2--5 mL/mol of phosphate). A description of the instrument developed for this study is also included.