Avian serum. cap alpha. /sub 1/-glycoprotein, hemopexin, differing significantly in both amino acid and carbohydrate composition from mammalian (. beta. -glycoprotein) counter parts
The physicochemical characteristics of chicken hemopexin, which can be isolated by heme-agarose affinity chromatography, is compared with representative mammalian hemopexins of rat, rabbit, and human. The avian polypeptide chain appears to be slightly longer (52 kDa) than the human, rat, or rabbit forms (49 kDa), and also the glycoprotein differs from the mammalian hemopexins in being an ..cap alpha../sub 1/-glycoprotein instead of a ..beta../sub 1/-glycoprotein. The distinct electrophoretic mobility probably arises from significant differences in the amino acid composition of the chicken form, which, although lower in serine and particularly in lysine, has a much higher glutamine/glutamate and agrinine content, and also a higher proline, glycine, and histidine content, than the mammalian hemopexins. Compositional analyses and /sup 125/I concanavalin A and /sup 125/I wheat germ agglutinin binding suggest that chicken hemopexin has a mixture of three fucose-free N-linked bi- and triantennary oligosaccharides. In contrast, human hemopexin has give N-linked oligosaccharides and an additional O-linked glycan blocking the N-terminal threonine residue, while the rabbit form has four N-linked oligosaccharides. In keeping with the finding of a simpler carbohydrate structure, the avian hemopexin shows only a single band on polyacrylamide gel electrophoresis under both nondenaturing and denaturing conditions, whereas the hemopexins of the three mammalian species tested show several bands. In contrast, the isoelectric focusing pattern of chicken hemopexin is very complex, revealing at least nine bands between pH 4.0 and pH band 5.0, while the other hemopexins show a broad smear of multiple ill-defined bands in the same region.Results indicate the hemopexin of avians differs substantially from the hemopexins of mammals, which show a notable similarity with regard to carbohydrate structure and amino acid composition.
- Research Organization:
- New York Hospital-Cornell Medical Center, NY
- OSTI ID:
- 6525056
- Journal Information:
- Biochemistry; (United States), Vol. 25:21
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GLUCOPROTEINS
CONFIGURATION INTERACTION
MOLECULAR STRUCTURE
AMINO ACID SEQUENCE
BLOOD SERUM
CARBOHYDRATES
CHEMICAL COMPOSITION
CHICKENS
CONCANAVALIN
ELECTROPHORESIS
IODINE 125
LABELLED COMPOUNDS
AGGLUTININS
ANIMALS
ANTIBODIES
BETA DECAY RADIOISOTOPES
BIRDS
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
FOWL
HEMAGGLUTININS
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPES
LECTINS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PROTEINS
RADIOISOTOPES
SACCHARIDES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques