Protein glycosylation structure

A. Varki, Biological roles of oligosaccharides all of the theories are correct, Gtycobiology 3 97, (1993) H. Lis and N. Sharon, Protein glycosylation-structural and functional aspects, Eur. J. Biochem. 218 1, (1993) and references therein. 

Fukuda M. The biology of glycoconjugates. Glycoconj J 1993 10 127-130. Lis H, Sharon N. Protein glycosylation—structural and functional-aspects. Eur J Biochem 1993 218 1-27. 

Lis, H., Sharon, N. Protein glycosylation structural and functional aspects. Eur. J. Biochem.,... 

Protein folding Glycosylation can effect local protein secondary structure and help direct folding of the polypeptide chain... 

HPLC-LTQ/FTMS N-Unked glycosylation structures in human plasma HPLC-Ion Trap MS Proteins expressing differences among isolates of Meloidogyne spp. HPLC-MALDI Monosaccharide anhydride levoglucosan, galactosan, and mannosan in the... 

Mannose is primarily found in mammalian N-linked glycoproteins as part of core structures containing the tri-Man core [a-D-Man-(1 3)-a-D-Man-(1 6)-Man]. However, in the glycoproteins of yeast and molds, mannose, primarily a-D-Man-(1 2)-a-D-Man and a-D-Man-(1 6)-a-D-Man, has been found a-linked to Ser or Thr. 244 Expression of glucoamylase G1 in Aspergillus niger 245 and human IGF-I (somatomedin C) in Saccharomyces cerevisiae 246 resulted in proteins glycosylated with mannose at Ser and Thr. 

Although sterols like cholesterol are not synthesized de novo by parasitic flatworms, they do possess an active mevalonate pathway (Fig. 20.3) (reviewed in Coppens and Courtoy, 1996). This pathway has been studied in 5. mansoni, and all available evidence indicates that it is similar to the lipid metabolism seen in F. hepatica. The mevalonate pathway was shown to be used by 5. mansoni for the synthesis of dolichols for protein glycosylation, of quinones as electron transporters in the respiratory chain and of farnesyl and geranylgeranyl pyrophosphates as substrates for the isopreny-lation of proteins (Chen and Bennett, 1993 Foster et a/., 1993). A key enzyme in the mevalonate pathway is 3-hydroxymethylglutaryl-CoA reductase (HMG-CoA reductase) and it was shown that the schistosomal enzyme differs from the mammalian type, both structurally and in its regulatory properties (Rajkovic et ai, 1989 Chen et at., 1991). Farnesyl pyrophosphate plays a key role in the mevalonate pathway as it is the last common substrate for the synthesis of all end products (Fig. 20.3). As mentioned already, the branch leading from farnesyl pyrophosphate via squalene to cholesterol is not operative in parasitic flatworms, whereas the other branches are active, at least in S. mansoni and probably also in F. hepatica and FI. diminuta. 

Fig. 21.3. Protein glycosylation of S. mansoni cercariae. Cercarial /V-glycan structures were reported by Khoo et ai. (2001) [1], O-glycan structures were elucidated by Fluang et ai. (2001) [2] and Khoo et ai. (1995) [3],...

Fig. 21.7. Glycosphingolipids and protein glycosylation of Cyclophyllida. Glycolipids of E. multilocularis were analysed by Persat et al. (1990) [1] and (1992) [2]. Glycolipids of T. crassiceps and M. coturnix were characterized by Dennis et al. (1992) [3] and Nishimura etal. (1991) [4], respectively. The major glycolipid of T. solium was analysed by Lopez-Marin etal. (2002) [5], Cer, ceramide. A/-glycans of E. granulosus and O-glycans of . multilocularis were described by Khoo etal. (1997c) [6] and Hulsmeier et al. (2002) [7], respectively. Possible Gala1-4)Gal1- structural elements are boxed.

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