Evolution of putrescine N-methyltransferase from spermidine synthase demanded alterations in substrate binding.

Putrescine N-methyltransferase (PMT) catalyses S-adenosylmethionine (SAM)-dependent methylation of putrescine in tropane alkaloid biosynthesis. PMT presumably evolved from the ubiquitous spermidine synthase (SPDS). SPDS protein structure suggested that only few amino acid exchanges in the active site were necessary to achieve PMT activity.

Putrescine N-methyltransferase--the start for alkaloids.

Putrescine N-methyltransferase (PMT) catalyses S-adenosylmethionine (SAM) dependent methylation of the diamine putrescine. The product N-methylputrescine is the first specific metabolite on the route to nicotine, tropane, and nortropane alkaloids. PMT cDNA sequences were cloned from tobacco species and other Solanaceae, also from nortropane-forming Convolvulaceae and enzyme proteins were synthesised in Escherichia coli.

Colorimetric activity measurement of a recombinant putrescine N-methyltransferase from Datura stramonium.

Putrescine N-methyltransferase (PMT, EC 2.1.1.