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Phytochemical studies on tobacco alkaloids XIV. The occurrence and properties of putrescine N-methyltransferase in tobacco roots 总被引:1,自引:0,他引:1
MIZUSAKI SHIGENOBU; TANABE YOKO; NOGUCHI MASAO; TAMAKI EINOSUKE 《Plant & cell physiology》1971,12(4):633-640
Putrescine N-methyltransferase, a new enzyme catalyzing theformation of N-methylputrescine from putrescine and S-adenosyl-L-methioninewas found in roots of tobacco plants. The enzyme was purified30-fold from crude extracts of tobacco roots. NMethylputrescinewas identified as the reaction product by comparison with theauthentic compound. The enzyme had a pH optimum between pH 8and 9, and a molecular weight of about 60,000, as determinedby gel filtration. Km values for putrescine and 5-adenosyl-L-methioninewere 4.0 x 104 M and 1.1 x 104 M, respectively.Enzyme activity was inhibited by N-chloromercuribenzoate andAg+. No cofactors were required. Of the various substrates tested,only putrescine served as a methyl acceptor. The enzyme waslocalized exclusively in the roots and its activity was greadyenhanced by decapitation. The presence of putrescine N-methyltransferase in tobacco rootsstrongly suggests that N-methylputrescine participates as anintermediate in nicotine biosynthesis. (Received March 2, 1971; ) 相似文献
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