Transient-state kinetic analysis of urocanase

A covalent NAD intermediate in the urocanase reaction

“…Our results, although derived from the study of a substrate analogue rather than the actual substrate, would seem relevant to the events occurring on the enzyme upon binding urocanate since recent reports indicate that urocanase catalyzes a solvent exchange of the 5 hydrogen of both imidazolepropionate and urocanate (Egan et al, 1981; Gerlinger & Retey, 1980). In addition, the following paper (Matherly et al, 1982) presents kinetic evidence for the existence of a reaction intermediate involving NAD and urocanate or imidazolepropionate.…”

“…A preliminary account of these findings has previously appeared (Phillips & Matherly, 1980). The following paper (Matherly et al, 1982) provides kinetic evidence that an analogous complex involving urocanate itself forms during catalysis.…”