Inhibition of Streptomyces chromofuscus phospholipase D activity by dichloro-(2,2':6',2'-terpyridine)-platinum (II) dihydrate

To determine the catalytic site of Streptomyces chromofuscus phospholipase D (PLD), which lacks an HKD motif, we examined the effects of inhibitors on the hydrolytic activity of the PLD by comparing it with cabbage and Streptomyces PLDs, which have two HKD motifs. We showed that dichloro-(2,2':6',2'-terpyridine)-platinum (II) dihydrate, a His- and Cys-directed chemical modifier, had inhibitory effects on the activities of all types of PLD examined. On the other hand, N-ethylmaleimide, a thiol-directed modifier had no such effects on PLD activity. These results suggest that the His residue plays an important role in the activity of Streptomyces chromofuscus PLD.