- Molecular and Structural Characterization of a Promiscuous C-Glycosyltransferase from Trollius chinensis
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Herein, the catalytic promiscuity of TcCGT1, a new C-glycosyltransferase (CGT) from the medicinal plant Trollius chinensis is explored. TcCGT1 could efficiently and regio-specifically catalyze the 8-C-glycosylation of 36 flavones and other flavonoids and could also catalyze the O-glycosylation of diverse phenolics. The crystal structure of TcCGT1 in complex with uridine diphosphate was determined at 1.85 ? resolution. Molecular docking revealed a new model for the catalytic mechanism of TcCGT1, which is initiated by the spontaneous deprotonation of the substrate. The spacious binding pocket explains the substrate promiscuity, and the binding pose of the substrate determines C- or O-glycosylation activity. Site-directed mutagenesis at two residues (I94E and G284K) switched C- to O-glycosylation. TcCGT1 is the first plant CGT with a crystal structure and the first flavone 8-C-glycosyltransferase described. This provides a basis for designing efficient glycosylation biocatalysts.
- He, Jun-Bin,Zhao, Peng,Hu, Zhi-Min,Liu, Shuang,Kuang, Yi,Zhang, Meng,Li, Bin,Yun, Cai-Hong,Qiao, Xue,Ye, Min
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supporting information
p. 11513 - 11520
(2019/07/16)
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- Towards the synthesis of glycosylated dihydrochalcone natural products using glycosyltransferase-catalysed cascade reactions
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Regioselective O-β-D-glucosylation of flavonoid core structures is used in plants to create diverse natural products. Their prospective application as functional food and pharmaceutical ingredients makes flavonoid glucosides interesting targets for chemical synthesis, but selective instalment of a glucosyl group requires elaborate synthetic procedures. We report glycosyltransferase-catalysed cascade reactions for single-step highly efficient O-β-D-glucosylation of two major dihydrochalcones (phloretin, davidigenin) and demonstrate their use for the preparation of phlorizin (phloretin 2′-O-β-d-glucoside) and two first-time synthesised natural products, davidioside and confusoside, obtained through selective 2′- and 4′-O-β-d-glucosylation of the dihydroxyphenyl moiety in davidigenin, respectively. Parallel biocatalytic cascades were established by coupling uridine 5′-diphosphate (UDP)-glucose dependent synthetic glucosylations catalysed by herein identified dedicated O-glycosyltransferases (OGTs) to UDP dependent conversion of sucrose by sucrose synthase (SuSy; from soybean). The SuSy reaction served not only to regenerate the UDP-glucose donor substrate for OGT (up to 9 times), but also to overcome thermodynamic restrictions on dihydrochalcone β-d-glucoside formation (up to 20% conversion and yield enhancement). Using conditions optimised for overall coupled enzyme activity, target 2′-O- or 4′-O-β-d-glucoside was obtained in ≥88% yield from reactions consisting of 5 mM dihydrochalcone acceptor, 100 mM sucrose, and 0.5 mM UDP. Davidioside and confusoside were isolated and their proposed chemical structures confirmed by NMR. OGT-SuSy cascade transformations present a green chemistry approach for efficient glucosylation in natural products synthesis. the Partner Organisations 2014.
- Gutmann, Alexander,Bungaruang, Linda,Weber, Hansjoerg,Leypold, Mario,Breinbauer, Rolf,Nidetzky, Bernd
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supporting information
p. 4417 - 4425
(2014/11/08)
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- Exploring the catalytic promiscuity of a new glycosyltransferase from Carthamus tinctorius
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The catalytic promiscuity of a new glycosyltransferase (UGT73AE1) from Carthamus tinctorius was explored. UGT73AE1 showed the capability to glucosylate a total of 19 structurally diverse types of acceptors and to generate O-, S-, and N-glycosides, making it the first reported trifunctional plant glycosyltransferase. The catalytic reversibility and regioselectivity were observed and modeled in a one-pot reaction transferring a glucose moiety from icariin to emodin. These findings demonstrate the potential versatility of UGT73AE1 in the glycosylation of bioactive natural products.
- Xie, Kebo,Ridao, Chen,Li, Jianhua,Wang, Ruishan,Chen, Dawei,Dou, Xiaoxiang,Dai, Jungui
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supporting information
p. 4874 - 4877
(2015/04/27)
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- A stilbene and dihydrochalcones with radical scavenging activities from Loiseleuria procumbens
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A new dihydrochalcone, 6-Acetylphloridzosid, was isolated from the whole plant of Loiseleuria procumbens (L.) Desv. and identified as 2'-O-(6-O-acetylglucopyranosyl)-4,4',6'-trihydroxydihydrochalcone by spectroscopic methods. In addition, one stilbene and three other dihydrochalcones were identified as (E)-piceid, phloretin (2',4,4',6'-tetrahydroxydihydrochalcone), phloridzosid (2'-O-glucopyranosyl-4,4',6'-trihydroxydihydrochalcone) and asebotin (2'-O-glucopyranosyl-4'-methoxy-4,6'-dihydroxydihydrochalcone), respectively. Some of these compounds showed scavenging properties towards the 2,2-diphenyl-1-picrylhydrazyl radical and antioxidant properties in a test with lysozyme. (C) 2000 Elsevier Science Ltd.
- Cuendet, Muriel,Potterat, Olivier,Salvi, Aline,Testa, Bernard,Hostettmann, Kurt
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p. 871 - 874
(2007/10/03)
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- Cosmetic composition
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A composition for topical application to the skin in order to promote the repair of photo-damaged or aged skin and/or to reduce or prevent damaging effects of ultra-violet light on skin and/or to lighten the skin comprising a hydrocalchone of general structure: STR1 wherein R1, R2 and R3, which may be the same or different, represent H, --OH, --OR or --COR (where R is a C1-20 alkyl group); R4, R5, R6 and R7, which may be the same or different, represent H or --COR (where R is as herein before defined). Optional additional ingredients include sunscreens and other skin lightening skin lightening agents, particularly retinol or derivatives thereof.
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