Transferase glycosyl

The glycosyl transferases have, like the glycoside hydrolases and transglycosy-lases, been classified into families on the basis of sequence similarities and the families are likewise available on CAZy. Most glycosyl transferases are membrane bound and this has limited the number of crystal structures (mostly of engineered enzymes without their membrane anchors) that are available. It has 

Important evidence that glycosyl transfer from activated donors with retention or inversion can indeed be catalysed by very similar protein folds comes from an oc-mannopyranosyl glycerate synthetase with a GTA fold, which according to amino acid sequence belongs to (inverting) GT 2, but catalyses 

The two protein folds associated with glycosyl transferases (a) GTA and (b) These greyscale ribbon diagrams were kindly provided 

The nucleotide diphosphates can be obtained by different approaches. Chemical synthesis provides an attractive route to these activated 

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As detailed structural information is obtained from a greater diversity of parasitic nematodes it is expected that the occurrence of stage-specific carbohydrate antigens, and therefore stage-specific glycosyl transferase activities, will be identified as a common characteristic. 

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

High selectivity and substrate specificity of glycosyl transferases make them valuable catalysts for special linkages in polymer-supported synthesis. There is, however, still a rather limited set of enzymes available to date, and the need to synthesize a variety of natural and non-natural oligosaccharides prevails. Particularly with regard to combinatorial approaches, chemical solid-phase oligosaccharide synthesis promises to meet the demands most effectively. 

A hexaglycine spacer was attached to the solid support to give a substitution of 0.2 mmol g of dry silica and the excess amino groups were then capped using acetic anhydride. In the next step a selectively cleavable, a-chymotrypsin sensitive, phenylalanine ester (2) was implemented for the release of the products from the solid support under mild conditions. Subsequently it was transformed to (3) followed by reactions with glycosyl transferases to yield (4). Finally, the desired glycopeptide was cleaved from the solid support in high yield by treatment of (4) with a-chymotrypsin (Scheme 10.1). 

Starch Liquefaction with a Highly Thermostable Cyclodextrin Glycosyl Transferase from Thermoanaerobacter Species... 

Table m. Saccharifications From Cyclodextrin Glycosyl Transferase Jetting... 

Recent developments in the enzymatic synthesis of carbohydrates can be classified into four approaches 1) asymmetric C-C bond formation catalyzed by aldolases (1-10 2) enzymatic synthesis of carbohydrate synthons (loll) 3) asymmetric glycosidic formation catalyzed by glycosidases (12.-17) and glycosyl transferases (18-23.) and 4) regioselective transformations of sugars and derivatives (24-25). These enzymatic transformations are stereoselective and carried out under mild conditions with minimum protection of functional groups. They hold promise in preparative carbohydrate synthesis. In connection with this book, we focus on the first two approaches. 

Tardioli, P.W., Zanin, G.M. and de Moraes, F.R, Production of cyclodextrins in a fluidized-bed reactor using cyclodextrin-glycosyl-transferase, Appl. Biochem. Biotech., 84 (2000) 1003-1020. 

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