Study design: D-penicillamine (D-pen) was tested on mouse artoa rings for its vasodilatory effect as a possible cysteine analogue and its effect on H2S biosynthesis.
Results: No vasodilatory effect was observed. D-pen did not function as a substrate to replace L-cysteine, but it reduced L-cysteine-induced vasodilatation by inhibiting H2S biosynthesis. CSE was inhibited selectively by D-pen in pyridoxal-5‘-phosphate-dependent manner.
Conclusions: Results indicate that D-pen could act as a selective CSE inhibitor accounting for a beneficial effect of D-pen in rheumatoid arthritis patients, where H2S has proved to be harmful.