Differential inhibition of serine proteinases by rabbit alpha 1-proteinase inhibitors F and S

Interactions of alpha-1-antichymotrypsin, alpha-1-proteinase inhibitor, and alpha-2-macroglobulin with the fungal enzyme, seaprose

The Semi-alkaline proteinase (Seaprose) from Aspergillus melleus has been tested for its ability to either inactivate or form complexes with three human plasma proteinase inhibitors, alpha-2-macroglobulin, alpha-1-antichymotrypsin and alpha-1-proteinase inhibitor. alpha-2-Macroglobulin was found to inhibit Seaprose, with two mol of enzyme being complexed per mol of inhibitor. However, alpha-1-proteinase inhibitor was rapidly inactivated by the fungal enzyme as a result of cleavage of the inhibitor, primarily at the P1-P'1 reactive site. Curiously, alpha-1-antichymotrypsin was found to form complexes with Seaprose and also be inactivated by this inhibitor. Apparently, the enzyme can recognize two sites within the reactive site loop of the inhibitor, one at the P4-P'5 position, resulting in inactivation, and one presumably at the P1-P'1 reactive site which results in complex formation. The fact that Seaprose can so rapidly inactivate alpha-1-proteinase inhibitor, the primary regulator of neutrophil elastase, indicates that Seaprose would be a rather poor choice for therapy in individuals with bronchial mucus hypersecretion.

Isolation and characterization of sheep alpha 1-proteinase inhibitor

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.

Comparison of antiproteolytic activities of alpha-1-proteinase inhibitors from the plasma of some mammalian species

Alpha-1-proteinase inhibitors isolated from plasmas of horse, ox, pig, rabbit and man were used for determination of some kinetic parameters of interaction with three horse leucocyte proteinases and bovine pancreatic trypsin and chymotrypsin. Effective molar ratio of enzyme-to-inhibitor, inactivation rate constant and inhibition constant were measured. In horse, ox, pig and rabbit two principal electrophoretic forms of alpha 1-PI could be distinguished. Both forms effectively inhibited trypsin but usually only one form reacted promptly and stoichiometrically with chymotrypsin and leucocyte elastases. It appears that genetic variability and functional heterogeneity of multiple forms of alpha 1-PI as well as lack of other tissue inhibitors of proteinases may be responsible for lung emphysema occurring in man and horse.

Proteinase inhibitors in rat serum. Purification and partial characterization of three functionally distinct trypsin inhibitors

Three different serine proteinase inhibitors were isolated from rat serum and purified to apparent homogeneity. One of the inhibitors appears to be homologous to alpha 1-proteinase inhibitor isolated from man and other species, but the other two, designated rat proteinase inhibitor I and rat proteinase inhibitor II, seem to have no human counterpart. alpha 1-Proteinase inhibitor (Mr 55000) inhibits trypsin, chymotrypsin and elastase, the three serine proteinases tested. Rat proteinase inhibitor I (Mr 66000) is active towards trypsin and chymotrypsin, but is inactive towards elastase. Rat proteinase inhibitor II (Mr 65000) is an effective inhibitor of trypsin only. Their contributions to the trypsin-inhibitory capacity of rat serum are about 68, 14 and 18% for alpha 1-proteinase inhibitor, rat proteinase inhibitor I and rat proteinase inhibitor II respectively.

Isolation of rat alpha-fetoprotein from Morris hepatoma 7777

1. Tissue slices from Morris hepatoma 7777 were incubated for 3 hr in Krebs-Ringer-bicarbonate solution and the cell-free supernatants were used for isolating alpha-fetoprotein. 2. Purification procedure included salting out with ammonium sulphate, affinity chromatography (either Concanavalin A-Sepharose or Cibacron-Blue-Sepharose), hydrophobic chromatography and preparative polyacrylamide gel electrophoresis (PAGE). 3.alpha-Fetoprotein was obtained with a yield of approx. 10% and in pure form, as judged from crossed immunoelectrophoresis and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE).