Enzymes glycosyltransferases

The GAGs are synthesized by the sequential actions of a battery of specific enzymes (glycosyltransferases, epimerases, suhotransferases, etc) and are degraded by the sequential action of lysosomal hydrolases. Genetic deficiencies of the latter result in mucopolysaccharidoses (eg, Hurler syndrome). 

Oligosaccharides are synthesized through the action of specific enzymes, glycosyltransferases, which catalyze the... 

As a final comment, let us recall that a further complication in the queuititative, structural analyis of certain carbohydrate polymers may result from the fact that oligo- and polysaccharides, whether free or attached to proteins, are not primary gene products (in contrast to polypeptide chains which are under direct control of the genetic code). They are, in fact synthesized by enzymes (glycosyltransferases) in the absence of any template. This synthesis may not be very accurate, and can result in microheterogeneity in heterosaccharide chains. 

Previous enzyme Certain glycosyltransferases will only act on an oligosaccharide chain If It has already been acted upon by another processing enzyme. ... 

Appropriate nucleotide sugars and highly specific Golgi-located glycosyltransferases are employed to synthesize the oligosaccharide chains of GAGs. The one enzyme, one linkage relationship appears to hold here,... 

Highly selective enzymatic synthesis using glycosyltransferases (GTFs), an approach restricted by the limited availability of Leloir-type enzymes, and expensive nucleotide-activated substrates... 

Glycosidases are rather undemanding in the choice of substrates, which greatly broadens their applications compared to glycosyltransferases. However, they also suffer from several significant drawbacks, such as low regioselectivity and yields. Thus, the choice of an appropriate attitude and an enzyme type remains strongly dependent on the specific application. 

A typical multi-enzyme reaction, presented in diverse variations, comprises the combined use of a glycosidase and a glycosyltransferase. If they are applied in one pot, the glycosidase product is directly processed by... 

Transfer of glycosyl residues to saccahride acceptors under catalysis by glycosyltransferases has been studied in recent years (85,88,89). In contrast to chemical glycosylation, enzymic extensions of the saccharide chain of... 

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