Mechanistic evidence for a front-side, S(N)i-type reaction in a retaining glycosyltransferase
Cited 47 times inCited 41 times in
- Mechanistic evidence for a front-side, S(N)i-type reaction in a retaining glycosyltransferase
- Lee, Seung Seo; Hong, Sung You; Errey, James C.; Izumi, Atsushi; Davies, Gideon J.; Davis, Benjamin G.
- SUBSTRATE-ASSISTED CATALYSIS; ENZYMATIC GLYCOSYL TRANSFER; TRANSITION-STATE; ALPHA-GALACTOSYLTRANSFERASE; TREHALOSE PHOSPHORYLASE; NEISSERIA-MENINGITIDIS; SCHIZOPHYLLUM-COMMUNE; COVALENT INTERMEDIATE; GLUCOSYL TRANSFER; ACTIVE-SITE
- Issue Date
- NATURE PUBLISHING GROUP
- NATURE CHEMICAL BIOLOGY, v.7, no.9, pp.631 - 638
- A previously determined crystal structure of the ternary complex of trehalose-6-phosphate synthase identified a putative transition state-like arrangement based on validoxylamine A 6'-O-phosphate and uridine diphosphate in the active site. Here linear free energy relationships confirm that these inhibitors are synergistic transition state mimics, supporting front-face nucleophilic attack involving hydrogen bonding between leaving group and nucleophile. Kinetic isotope effects indicate a highly dissociative oxocarbenium ion-like transition state. Leaving group O-18 effects identified isotopically sensitive bond cleavages and support the existence of a hydrogen bond between the nucleophile and departing group. Bronsted analysis of nucleophiles and Taft analysis highlight participation of the nucleophile in the transition state, also consistent with a front-face mechanism. Together, these comprehensive, quantitative data substantiate this unusual enzymatic reaction mechanism. Its discovery should prompt useful reassessment of many biocatalysts and their substrates and inhibitors.
- ; Go to Link
- Appears in Collections:
- ECHE_Journal Papers
- Files in This Item:
can give you direct access to the published full text of this article. (UNISTARs only)
Show full item record
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.