Diamine Oxidase from Cultured Roots of Hyoscyamus niger

Abstract

Diamine oxidase was partially purified from cultured roots of Hyoscyamus niger L. that produce considerable amounts of tropane alkaloids, and then characterized. N-Methylated amines inhibited the activity of the enzyme more strongly than the corresponding primary amines. N-Methylputrescine was the best substrate of those studied, the respective K(m) values for it and for putrescine and cadaverine being 0.33, 2.85, and 6.25 millimolar. The specificity constants V(max)/K(m) for putrescine and cadaverine were 11 and 1% of the constant for N-methylputrescine. Marked specificity for the N-methylated diamine would enable the Hyoscyamus enzyme to function specifically in tropane alkaloid biosynthesis.