Characterization of an O-methyltransferase from soybean.
O-methyltransferases (OMTs) catalyze the transfer of a methyl group from S-adenosine-L-methionine to a hydroxyl group of an acceptor molecule to form methyl ether derivatives and can modify the basic backbone of a secondary metabolite. A new O-methyltransferase, SOMT-9, was cloned from Glycine max and found to encode a protein whose molecular weight is 27-kDa. SOMT-9 was expressed as a GST-fusion protein in Escherichia coli and several compounds such as caffeic acid, esculetin, narigenin, kaempferol, quercetin, and luteolin were tested as putative substrates of SOMT-9. HPLC and NMR results showed that SOMT-9 transfers a methyl group to the 3'-OH group of substrates having ortho-hydroxyl groups. SOMT-9 showed the highest affinity for quercetin, suggesting that SOMT-9 uses a flavonoid as a substrate. Based on its molecular weight and substrate specificity, SOMT-9 belongs to a new class of OMT and is likely to be involved in the biosynthesis of isorhamnetin.
Kim
B G
BG
Bio/Molecular Informatics Center, Division of Bioscience and Biotechnology, KonKuk University, Seoul 143-701, Korea.
Lee
H J
HJ
Park
Y
Y
Lim
Y
Y
Ahn
J-H
JH
D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D008969:Molecular Sequence Data; D011497:Protein O-Methyltransferase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013025:Glycine max / Q000201:enzymology* / Q000235:genetics; D013379:Substrate Specificity
D011497:Protein O-Methyltransferase