Title : Location and characterization of
the three carbohydrate prosthetic groups of human
protein HC
Abstract :
- Three different carbohydrate prosthetic groups associated to three chymotryptic peptides , Q1, Q2 and Q3, were isolated from the reduced and carboxymethylated human protein HC
- The first oligosaccharide forms an O-glycosidic linkage with a threonine residue at position 5 in the polypeptide chain of protein HC
- The second and third carbohydrate prosthetic groups form N-linkages with asparagine residues at positions 17 and 96
- Oligosaccharides present in Q1 contain 1 residue of NANA, 2 of GalNAc and 1 of Gal corresponding to the following structure: -O-GalNAc-GalNAc-Gal-NANA.
- Q2 contains 3 NANA, 9 GlcNAc, 2 Gal and 3 Man, and Q3 contains 2 NANA, 5 GlcNAc, 1 Gal and 2 Man.
- The sugar compositions of Q2 and Q3 oligosaccharides are compatible with that of the complex kind
- The amount of oligosaccharides present in Q1, Q2 and Q3 corresponded respectively to 3.0%, 12.2% and 7.3% of the weight of protein HC
- No difference was found between the carbohydrate composition of urinary and plasma protein HC