SELECTIVE-INHIBITION OF MAMMALIAN DIAMINE OXIDASE BY AQUATIC BIOTOXINS

The inhibitory activity of saxitoxin and tetrodotoxin on diamine oxida se and S-adenosyl-L-methionine decarboxylase from mammalian sources ha ve been analysed. Unlike tetrodotoxin, saxitoxin was a reversible non- competitive inhibitor of pig kidney diamine oxidase with an estimated K-i of 140 mu M. S-Adenosyl-L-methionine decarboxylase from a highly p urified source was not affected by the concentrations tested of either biotoxin. A possible analytical application of this finding is discus sed.