Characterization of serine protease inhibitors from wild cocoons of Antheraea yamamai and Bombyx mandarina in comparison with those from Bombyx mori
2000
Kurioka, A. (Silk Science Research Inst., Tokyo (Japan)) | Yamazaki, M. | Hirano, H.
Serine protease inhibitors derived from wild cocoons of Antheraea yamamai and Bombyx mandarina were characterized on native PAGE and Tricine SDS-PAGE in order to compare them with B. mori cocoon shell-associated trypsin inhibitors (BmoCSTIs). On Tricine SDS-PAGE, three inhibitors of high molecular weight were found in the cocoon of A. yamamai. These were designated AyCSTI, AyCSCI-Al and AyCSCI-A2. The molecular masses were estimated to be 20kDa for AyCSCIs-Al and A2, and 18kDa for AyCSTI. Tricine SDS-PAGE of these inhibitors under reducing conditions gave molecular mass estimates of 20kDa for AyCSCIs-Al and A2, and 9kDa for AyCSTI, suggesting that AyCSCIs-Al and A2 are monomers and AyCSTI is a dimer. AyCSCIs-Al and A2 showed inhibitory activity towards bovine alpha-chymotrypsin and AyCSTI towards bovine trypsin. AyCSCIs-Al and A2 were acid-stable, but heat-labile, whereas AyCSTI was heat- and acid-stable. The cocoon of B. mandarina, was found to contain an inhibitor of low molecular mass (6kDa), designated BmaCSTI, which inhibited trypsin and alpha-chymotrypsin probably at the samereactive site. The present analysis also indicated two B. mori trypsin inhibitors, BmoCSTI-I (15.9kDa) and BmoCSTI-II (5.8kDa) were able to inhibit alpha-chymotrypsin at a single reactive site. These results indicated that serine protease inhibitors of trypsin and alpha-chymotrypsin are common components of lepidopteran cocoons
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