Specific inhibition of the enzymic decarboxylation of S-adenosylmethionine by methylglyoxal bis(guanylhydrazone) and related substances

Methylglyoxal bis(guanylhydrazone) {1,1'-[(methylethanediylidene)-dinitrilo]diguanidine} is a very potent inhibitor of putrescine-activated S-adenosylmethionine decarboxylases from many different mammalian tissues, including sublines of mouse L1210 leukaemia that are resistant to the drug as well as sublines that are sensitive. The inhibition of purified rat ventral prostate S-adenosylmethionine decarboxylase is competitive with respect to the S-adenosylmethionine substrate, and is much greater in the presence than in the absence of the activator putrescine. Inhibition by the drug depends, among other things, on the nature of the aliphatic amines that can serve as stimulators of rat prostate S-adenosylmethionine decarboxylase. Effects of some congeners of methylglyoxal bis(guanylhydrazone) on the enzyme are described.