Bong-Gyu Kim

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The attachment of sugar to flavonoids enhances their solubility. Glycosylation is performed primarily by uridine diphosphate-dependent glycosyltransferases (UGTs). The UGT from Bacillus cereus, BcGT-1 transferred three glucose molecules into kaempferol. The structural analysis of BcGT-1 showed that its substrate binding site is wider than that of flavonoid(More)
Hydroxycinnamoyltransferases (HCTs) catalyze the transfer of the cinnamoyl moiety from hydroxycinnamoyl-CoA to various acceptors such as shikimic acid, quinic acid, hydroxylated acid, and glycerol. Four rice HCT homologues (OsHCT1-4) to tobacco HST were cloned, and OsHCT4 was expressed in Escherichia coli as a glutathione S-transferase fusion protein. Using(More)
Plant O-methyltransferases (OMTs) are known to be involved in methylation of plant secondary metabolites, especially phenylpropanoid and flavonoid compounds. An OMT, ROMT-9, was cloned and characterized from rice using a reverse transcriptase polymerase chain reaction (RT-PCR). The blast results for ROMT-9 showed a 73% identity with caffeic acid OMTs from(More)
Biotransformation of flavonoids using Escherichia coli harboring specific glycosyltransferases is an excellent method for the regioselective synthesis of flavonoid glycosides. Flavonol rhamnosides have been shown to contain better antiviral and antibacterial activities compared to flavonol aglycones. To synthesize flavonoid rhamnoside, a strain of E. coli(More)
Flavonoids found in plants most likely undergo a variety of modification reactions such as hydroxylation, glycosylation, and/or methylation. Among these, O-methylation has an effect on the solubility and thus on the antimicrobial activity of the flavonoids. We analyzed the conversion of naringenin with a methyltransferase, SOMT-2, from Glycine max. SOMT-2(More)
Many natural compounds are attached to sugars, and this influences their biological activities by altering molecular and cellular specificities. Among the different sugar moieties found in natural compounds, deoxyand aminosugars display the most variation. Here, we report that flavonoid deoxyaminosugar conjugates, which are rare in nature can be produced in(More)
O-Methylation, commonly found in synthesis of secondary metabolites of plants and micro-organisms, appears to transfer a methyl group to the hydroxyl group of the recipient which increases the hydrophobicity of the recipient. O-Methyltransferase (OMT), , was isolated and characterized from Streptomyces avermitilis MA-4680. Its amino acid sequence showed 68%(More)
Flavonoids consist of a large family of compounds, which has been estimated to be more than 10,000 compounds. The structural diversity of these compounds comes from different modification reactions. The O-methylation reaction is one of the most important modification reactions of flavonoids and the resulting O-methylated flavonoids have been shown to(More)
Flavonoids are predominantly found as glycosides in plants. The glycosylation of flavonoids is mediated by uridine diphosphate-dependent glycosyltransferases (UGT). UGTs attach various sugars, including arabinose, glucose, galactose, xylose, and glucuronic acid, to flavonoid aglycones. Two UGTs isolated from Arabidopsis thaliana, AtUGT78D2 and AtUGT78D3,(More)
Enzymatic glucosylation with glycosyltransferases can be used to regulate the water solubility of aglycone. The drawback of this process is the demand of UDP-glucose as a sugar donor. We made an in-frame fusion of the flavonoid O-glucosyltransferase (OsUGT-3) and sucrose synthase (AtSUS) genes. The resulting fusion protein, OsUGT3-AtSUS, was expressed in E.(More)