Glycolipid acceptor

The incubation mixture for the biosynthesis of glycosphingolipids usually includes an enzyme preparation, a glycosyl donor, a glycolipid acceptor, a detergent, and metal ions. Most of the glycosyltransferases are membrane bound and are usually associated with the microsomal... 

Kinetic Properties of Sialyltransferases. The sialyl-transferase activities with the endogenous glycoprotein and glycolipid acceptors in the standard assays (15) were linear with time for at least 60 min, while those with the exogenously added GMi and DS-fetuin were linear with time only for about 30 min (Figure 1). Activities were directly proportional to the amount of enzyme added up to 0.75 mg protein/assay (Figure 2). 

Other values obtained (20) in rat brain for the endogenous and exogenous glycolipid acceptors were 3-40 times smaller than the value reported here. The reasons for such marked discrepancies between the reported Km values are not clear. Conceivably, tissue differences and assay conditions in these other systems can contribute to such differences. Detergents, for example, were not used by Arce et al., (20). 

P4-GalT rV is a poorly acting enzyme and no activity could be detected with glycoprotein acceptors [172]. It has, however, notable activity with glycolipid acceptors and can support the synthesis of paragloboside. a-LA does not significantly induce the enzyme to act on Glc, but rather stimulates activity toward free GlcNAc [172]. 

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