Photomodification by Rose Bengal of NAD(P)H-Nitrate Reductase of Hansenula anomala

Abstract

The photoillumination of assimilatory nitrate reductase of Hansenula anomala in the presence of Rose Bengal caused a selective inactivation of NAD(P)H-linked activities. The potent protective effect of NAD(P)H suggests that the residue(s) modified by the treatment is involved in electron transport from NAD(P)H. From the observation that p-chloromercuribenzoate-treated enzyme was potomodified similarly to the native enzyme, the photomodified residue(s) is deduced not to be cysteine. The parallel decrease of NAD(P)H-nitrate reductase activity and the histidine contents suggests that histidine residue(s) is involved in this inactivation.