The N-acetylneuraminic acid content of five forms of human transferrin.
Biochim Biophys Acta
; 994(2): 161-5, 1989 Feb 02.
Article
in En
| MEDLINE
| ID: mdl-2910347
ABSTRACT
Five isoforms of human serum transferrin were separated by isoelectric focusing and their N-acetylneuraminic acid content was determined. The forms differed in isoelectric point by about 0.1 of a pH unit with the structural differences situated in the carbohydrate parts. Each form had one sialic acid molecule (NANA) less than the next most acidic form. GLC-MS showed that the most abundant form with isoelectric point 5.5 had two two-branched carbohydrate chains, each having the galactoses covered by terminal sialic acid. The form with isoelectric point 5.4 had one three-branched and one two-branched carbohydrate chain, and all branches terminated with a sialic acid residue. The form with isoelectric point 5.6 had a terminal galactose on one of its two two-branched carbohydrate chains. Comparison of the sialic acid content of the five transferrin forms and their carbohydrate structures showed that some of the forms expose terminal galactose without attracting the asialoglycoprotein receptors on hepatocytes.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Sialic Acids
/
Transferrin
Limits:
Humans
Language:
En
Journal:
Biochim Biophys Acta
Year:
1989
Document type:
Article
Affiliation country:
Sweden