Irreversible inhibition of mammalian and yeast S-adenosylmethionine decarboxylase by 1,1′-(methylethanediylidenedinitrilo)-bis(3-aminoguanidine)

Putrescine activated S-adenosylmethionine decarboxylases from rat liver and yeast are strongly inhibited on incubation with 1,1′-(methylethanediylidenedinitrilo)-bis(3-aminoguanidine). Inhibition cannot be reversed by dialysis or dilution and occurs more rapidly in the presence of putrescine. Protection against this inactivation is provided by the presence of methylglyoxal bis(guanylhydrazone) which is an analog of the inactivator and is known to be a potent but readily reversible inhibitor of the decarboxylase. Inactivation of S-adenosylmethionine decarboxylase activity by 1,1′-(methylethanediylidenedinitrilo)-bis(3-aminoguanidine) occurs in unfractionated liver homogenates and in rats treated with this compound which may therefore be of value in depressing spermidine synthesis in vivo.