Mechanism of Glycosylation

S. G. Withers, Mechanisms of glycosyl transferases and hydrolases, Carbohydr. Polym., 44 (2001) 325-337. 

Scheme 15 General mechanism of glycosylation. The hydroxyl group of serine attacks the activated anomeric carbon of UDP-activated sugars.

SCHEME 3.18 Mechanism of glycosylation involving n-pentenyl glycosides. 

Capasso JM, Hirschberg CB. Mechanisms of glycosylation and sulfation in the Golgi apparatus evidence for nucleotide sugar/nucleoside monophosphate and nucleotide sulfate/ nucleoside monophosphate antiports in the Golgi apparatus membrane. Proc. Natl. Acad. Sci. U.S.A. 1984 81 7051-7055. 

Zechel DL, Withers SG (1999) In Poulter CD (ed), Mechanisms of glycosyl transfer, Comprehensive Natural Products Chemistry, chapter 5, Elsevier, New York, p 279... 

Fig. 8. Glycosyl hydrolysis - inverting mechanism. The inverting mechanism of glycosyl hydrolysis utilizes a protonated acidic amino acid residue as a proton donor. A charged acidic amino acid residue opposite the proton donor activates water for nucleophilic attack by electrostatic repulsion. The remaining proton from the water protonates the residue to reset the active site with the roles now reversed...

Davies Gideon, Henrissat B (1995) Structures and mechanisms of glycosyl hydrolases. Structure 3 853-859... 

Scheme 2.17 General mechanism of glycosylation by means of glycosyl fluorides [49],...

Parodi, A. J., Lederkremer, G. Z., and Mendelzon, D. H. (1983). Protein glycosylation in Trypanosoma cruzi. The mechanism of glycosylation and structure of protein-bound oligosaccharides./. Biol. Chem. 258, 5589-5595. 

Deoxyfluoro- and deoxy-sugars are useful in studies both of binding interactions between carbohydrates and proteins, and in mechanisms of glycosyl transfer. This paper describes how we have used such analogues to measure hydrogen bond strengths in a carbohydrate/ protein complex of known structure. It proceeds to review how such substitutions affect the rates of glycosyl transfer in a non-enzymatlc model reaction and then applies this Information to the results obtained in our enzymatic system. 

Inverting and Retaining Mechanisms of Glycosyl Transfer. Mechanistically, glycosidases can be broadly classified into two main groups based on the overall stereochemical outcome of bond cleavage, retention or inversion, at the... 

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