Abstract
A serine proteinase inhibitor was isolated from carp, Cyprinus carpio, ordinary muscle by ammonium sulfate fractionation, heat treatment, column chromatography on DEAE-Sephadex A-50, gel nitration on Sephadex G-150, and preparative polyacrylamide gel electrophoresis. The final purified preparation of the inhibitor was' homogeneous as judged by polyacrylamide gel electrophoresis. The molecular weight of the inhibitor was about 100, 000 by gel filtration on Sephadex G-100, and 56, 000 by sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis after reduction with 2-mercaptoethanol. The inhibitor was stable over the range of pH 7.0 - 9.5 at 5°C for 15hr, but unstable below pH 4.5. The isoelectric point was about 5.3. Trypsin, α-chymotrypsin, and elastase were strongly inhibited by the inhibitor. Subtilisin BPN' and pronase were slightly inhibited, but pepsin, papain, and thermolysin were not inhibited. E•I complex from the inhibitor and elastase was stable to denaturing and reducing reagents such as SDS and 2-mercaptoethanol. On the basis of the properties described above, the proteinase inhibitor is most similar to the α1-proteinase inhibitor of human serum.
