title: Purification and partial characterization of an ostrich alpha 1-antichymotrypsin-like serum inhibitor.
abstract: alpha 1-Antichymotrypsin, a member of the serpins, is the predominant plasma inhibitor of neutrophil cathepsin G. The aim of this study was to purify ostrich alpha 1-antichymotrypsin and to compare its biochemical properties with those of other species. Ostrich alpha 1-antichymotrypsin was purified from serum by ammonium sulphate fractionation, QAE-Sephadex C-50 and phenyl-Toyopearl chromatography. N-terminal sequence, amino acid composition, molecular mass, isoelectric point and reaction with cathepsin G, elastase and chymotrypsin were determined. SDS-PAGE revealed a M, of 55,000 for ostrich alpha 1-antichymotrypsin and pI values of 6.8 and 4.1-4.3 were obtained. The amino acid composition revealed 444 residues and the N-terminal sequence of the first 20 residues revealed a homology of 30% when compared with several other alpha 1-antichymotrypsin sequences. Total inhibition of cathepsin G by ostrich alpha 1-antichymotrypsin was found at a 4:1 molar ratio of inhibitor to enzyme which was similar to that found for commercial alpha 1-antichymotrypsin. Immunological studies highlighted the lack of cross-reactivity between ostrich and human alpha 1-antichymotrypsin. The study indicated that ostrich alpha 1-antichymotrypsin-like molecule exhibited similar properties to human alpha 1-antichymotrypsin although there were notable differences.
authors.affiliation: Department of Biochemistry, University of Port Elizabeth, South Africa.
authors.forename: C L
authors.initials: CL
authors.lastname: Frost
authors.forename: R J
authors.initials: RJ
authors.lastname: Naudé
authors.forename: W
authors.initials: W
authors.lastname: Oelofsen
authors.forename: K
authors.initials: K
authors.lastname: Muramoto
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001717:Birds; D006801:Humans; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D015842:Serine Proteinase Inhibitors / Q000097:blood / Q000302:isolation & purification*; D013045:Species Specificity; D000514:alpha 1-Antichymotrypsin / Q000097:blood / Q000302:isolation & purification*
chemical_list: D015842:Serine Proteinase Inhibitors; D000514:alpha 1-Antichymotrypsin