Isolation of two novel proteinase inhibitors from hemolymph of silkworm larva, Bombyx mori. Comparison with human serum proteinase inhibitors.

Two protein proteinase inhibitors, anti-trypsin and anti-chymotrypsin, were isolated from the hemolymph of silkworm larva, Bombyx mori, using conventional gel filtration and ion exchange chromatography techniques. They had similar physicochemical properties, in molecular weight (42,000 for anti-trypsin and 43,000 for anti-chymotrypsin), in amino acid composition, and in CD spectrum. Further comparison of these characteristics with human serum inhibitors, alpha-1-proteinase inhibitor and alpha-1-antichymotrypsin, suggested the resemblance of silkworm and human inhibitors. But the N-terminal sequences were not homologous to each other and antiserum against each silkworm inhibitor only formed a precipitin lines with its own antigen. These results indicated differences in minute parts of the inhibitors.