Alan H. Colen

Spectrophotometric observation of a glutamate dehydrogenase-l-glutamate complex

Abstract Ultraviolet differential spectroscopic measurements show the existence of a glutamate dehydrogenase ( l -glutamate:NAD(P) + oxidoreductase (deaminating), EC 1.4.1.3)— l -glutamate complex. The spectral features resemble perturbation difference spectra of enzyme aromatic amino acid chromophores and allow the determination of the l -glutamate concentration dependence. The dissociation constant for this enzyme- l -glutamate complex was approximately 48 mM and was independent of enzyme concentration. The lack of interaction between the binding of l -glutamate and the activating monocarboxylic amino acids indicates that they bind at totally separate sites.