Glycoproteins enzymes with structure

Fibrinolytic effecting protease enzyme with glycoprotein structure relative mol mass ca. 30000. Isolation from the poison secretion (venom) of Agkistrodon rhodostoma (malayan pit viper) with chromatographic purification. 

The carbohydrate moiety of glycoproteins is added to a preformed protein molecule. Thus, the structure of the protein part is determined by the corresponding DNA structure, but the structure of the carbohydrate part is determined by the specificity of the enzymes (the structure of which is ultimately encoded in DNA as well) that catalyze the decoration of the protein once formed. The carbohydrate structures are generally quite complex and their formation is the product of several enzymes acting with several substrates. 

Other close structural analogues of saquinavir (17) incorporating the hydroxyethylamine isostere have been developed to provide potent inhibitors of HIV-1 protease. For example, palinavir (21) (Table III) inhibits the enzyme with a Kj of 0.03 nM and blocks viral replication with an EC50 of 7 nM This antiviral potency was not substantially affected by the addition of oci-acid glycoprotein at physiological concentrations however, 21 did show reduced activity against HIV-1 variants with active site mutations, including valine-32 to isoleucine and isoleucine-84 to valine (Lamarre et al., 1997). Pharmacokinetics in rats have been reported for palinavir. The compound exhibited an oral bioavailability of 20 to 30%, with a plasma half-life of 30 to 50 minutes. 

The substrate requirements, linkage specificity, and kinetic mechanism of an q -2,3-sialyltransferase have been compared with an a-2,6-sialyltransferase from porcine submaxillary mucin.The former enzyme will specifically modify glycoproteins and glycolipids which contain 2-acetamido-2-deoxy-3-O S-D-galactosyl-D-galactose sequences. The only acceptor substrates reported for the a-2,6-sialyltransferase are those glycoproteins containing the structure (58). ... 

L-asparagine have been isolated from human i-acid glycoprotein which had been degraded with neuraminidase and proteolytic enzymes. The structure (45) for these glycopeptides was established from a combination of sequential... 

An early analysis of the spleen enzyme showed the presence of hexose and hexo-samine A more recent study has demonstrated an enzyme from human hairy leukemic cells which appears identical to the purple spleen phosphatase, and which binds to ConA-Sepharose and is eluted with methylmannoside Very likely, therefore, the spleen enzyme, Uke uteroferrin, is a high mannose glycoprotein, but the structure of its carbohydrate has yet to be determined. In each protein the oligosaccharide chain appears to be attached to an asparagine residue (at position 97 in uteroferrin), since this residue was observable only after treatment with N-glycanase which removes N-asparagine-linked oUgosaccharides. ... 

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