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Location and characterization of the three carbohydrate prosthetic groups of human protein HC
Author(s) -
Escribano J.,
Lopex-Otin C.,
Hjerpe A.,
Grubb A.,
Mendez E.
Publication year - 1990
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(90)81531-r
Subject(s) - threonine , oligosaccharide , carbohydrate , residue (chemistry) , glycosidic bond , chemistry , asparagine , biochemistry , sugar , amino acid , serine , phosphorylation , enzyme
Three different carbohydrate prosthetic groups associated to three chymotryptic peptides, Ql, 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 Ga1NAc and 1 of Gal corresponding to the following structure: ‐O‐Ga1NAc‐Ga1NAc‐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.