Structural studies on porcine hemopexin

• Published in: International journal of biochemistry Vol. 22; no. 4; pp. 367 - 377
• Main Authors: Spencer, Harold T., Pete, Matthew J., Babin, Donald R.
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 1990
• Subjects: Amino Acids - analysis; Animals; Binding Sites; Electrophoresis, Polyacrylamide Gel; Heme; Hemopexin - isolation & purification; Male; Molecular Structure; Molecular Weight; Peptide Fragments - isolation & purification; Polymorphism, Genetic; serum; Swine
• ISSN: 0020-711X
• DOI: 10.1016/0020-711X(90)90139-T

1. 1. Porcine hemopexin was isolated from the serum of a single animal and purified to homogeneity. 2. 2. Porcine hemopexin has an apparent M w of 67,000, binds heme in a 1:1 molar ratio and consists of 24% N-linked oligosaccharides. The amino acid composition of porcine hemopexin compares well with the amino acid composition of human and rabbit hemopexins. 3. 3. Limited tryptic hydrolysis of apohemopexin generates stable peptides of apparent M w 42,000, 25,000, 24,000 and 21,000. The tryptic peptide of apparent M w 42,000 (peptide I) binds heme in a 1:1 molar ratio, consists of 33% N-linked oligosaccharides and is derived from the amino terminal of intact hemopexin. The three peptides of smaller- M w (collectively peptide II) represent the carboxyl terminal half of hemopexin, do not contain N-linked oligosaccharides and have no heme-binding capability. The M w heterogeneity of peptide II is likely due to cleavage at secondary sites. 4. 4. Under nondissociating electrophoresis two bands are resolved for hemopexin and peptide I. indicating the possibility of polymorphism in porcine hemopexin.