Differential interactions of rabbit plasma alpha-1-antiproteinases S and F with porcine trypsin.
Two major forms of rabbit plasma alpha-1-antiproteinase, S and F, were separated by affinity chromatography on Red Sepharose, and their modes of interaction with porcine trypsin were studied. The S form interacted with trypsin much more slowly than the F form, and the resulting complex partially retained the amidolytic and proteolytic activities towards benzoyl-L-arginine p-nitroanilide and remazol brilliant blue hide powder, respectively. This S form-trypsin complex also prevented the inactivation of bound trypsin by soybean trypsin inhibitor. In marked contrast, an equimolar complex of trypsin and the F form retained neither amidolytic nor proteolytic activity. These results suggest that the F form blocks the active site of trypsin while the S form does not bind directly to the active site, thereby preserving the catalytic potential of trypsin. No similar interaction was observed, however, between the S form and either bovine chymotrypsin or porcine pancreatic elastase. Both the S and F forms inactivated these proteinases in a stoichiometric manner with differing inhibitor/proteinase binding ratios. The S form showed about twofold greater capacity to inhibit elastase than the F form, whereas the reverse was the case for chymotrypsin.
Saito
A
A
Department of Biochemistry, Kinki University School of Medicine, Osaka.
Sinohara
H
H
D000595:Amino Acid Sequence; D000818:Animals; D002918:Chymotrypsin / Q000037:antagonists & inhibitors; D004591:Electrophoresis, Polyacrylamide Gel; D007527:Isoenzymes / Q000378:metabolism*; D010196:Pancreatic Elastase / Q000037:antagonists & inhibitors; D010449:Peptide Mapping; D011817:Rabbits; D013552:Swine; D014357:Trypsin / Q000378:metabolism*; D000515:alpha 1-Antitrypsin / Q000378:metabolism*
D007527:Isoenzymes; D000515:alpha 1-Antitrypsin; D002918:Chymotrypsin; D010196:Pancreatic Elastase; D014357:Trypsin