title: Isolation and characterization of sheep alpha 1-proteinase inhibitor.
abstract: Sheep plasma proteinase inhibitor, analogous to human alpha 1-proteinase inhibitor (alpha 1 PI), was isolated to homogeneity. Purification was achieved by using (NH4)2SO4 precipitation, concanavalin A-Sepharose chromatography, Mono Q ion-exchange chromatography and PAGE. Sheep alpha 1 PI had an Mr of 56,000, inhibited human leucocyte elastase, pig pancreatic elastase and bovine trypsin on a 1:1 molar basis and had a plasma concentration of 1.6 +/- 0.21 g/l (mean +/- S.D.). Amino acid/carbohydrate composition (15% glycosylated) was similar to that of human alpha 1 PI (16% glycosylated); N-terminal analysis to 31 residues revealed 48-52% identity between the human and sheep proteins. Sheep alpha 1 PI was susceptible to oxidative inactivation by chloramine-T. Re-activation with the use of methionine sulphoxide peptide reductase and dithiothreitol indicated the presence of a methionine residue at the active site. These results establish that sheep alpha 1 PI has functional and structural characteristics close to those of human alpha 1 PI.
authors.affiliation: Department of Medicine, Charing Cross and Westminster Medical School, London, U.K.
authors.forename: R
authors.initials: R
authors.lastname: Mistry
authors.forename: P D
authors.initials: PD
authors.lastname: Snashall
authors.forename: N
authors.initials: N
authors.lastname: Totty
authors.forename: A
authors.initials: A
authors.lastname: Guz
authors.forename: T D
authors.initials: TD
authors.lastname: Tetley
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002241:Carbohydrates / Q000032:analysis; D002846:Chromatography, Affinity; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D005779:Immunodiffusion; D007122:Immunoelectrophoresis; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D012689:Sequence Homology, Nucleic Acid; D012756:Sheep; D013379:Substrate Specificity; D000515:alpha 1-Antitrypsin / Q000235:genetics / Q000302:isolation & purification* / Q000494:pharmacology
chemical_list: D000596:Amino Acids; D002241:Carbohydrates; D000515:alpha 1-Antitrypsin