Studies On The Proteinase Inhibitor In The Spun Silk Insect's Cocoon

The protease inhibitor (PI) was extracted from six species of spun silk insects' cocoon , sericin cocoon and naked pupa separately. The PI activities was studied. The results showed that there were a large amount relatively PI in the Bombyx mori's cocoon, a small amount PI in the Antheraea yamamai ussurinsis's green cocoon and the Bombyx mandarina Butler cocoon, micro-amount in the Philosamia Cynthia ricini Boisduval cocoon and none in the Antheraea yamamai ussurinsis's yellow cocoon, Antheraea pernyi Guerin cocoon and Attacus cynthia pryeri Buter cocoon. A small amount PI in the sericin cocoon(Nd-s), and none PI in the sericin spunned by naked pupa(Nd).The furthermore studies on the PI in silkworm's cocoon was performed. The results showed that the content of PI was significant different among the silkworm strains and none significant different between female and male. The content in the FI was intermediate type between two parents' and inclined to the higher parent. What's more, in the silkworm's outer layer cocoon, were there more PI.The PI was extracted from 11 Chinese race's cocoon, 11 Japanese race's cocoon, 11 European race's cocoon, 11 polyvoltine race's cocoon separately. The PI activities and the correlativitv between the content of PI in the cocoon and some major economical character were studied. The results showed that the content of PI was significant different among the silkworm strains, and Chinese strain > Japanese strain > European strain > polyvoltine strain. The content of PI among the Chinese strain, Japanese strain and European strain was different from polyvoltine strain. A significant positive correlation between the content of PI in the cocoon and cocoon shell weight or cocoon shell rate, no significant correlation between the content of PI in the cocoon and cocoon weight, rate of dead worm cocoons, survival rate of larva or larva-pupa rate.After extracted roughly, purified with permeating and then purified by HPLC lastly, the PI of higher purity was acquired from one strain 82'$ inner layer or outer layer cocoon. The retrieved rate of inhibiting activity was one hundred percent. It was purified about fifty times more than only extracted roughly. There was only one protein's band on theTricine-SDS-PAGE. The molecule of PI in BI'S inner layer and outer layer cocoon both were about 7500Da.After the purified PI in silkworm'cocoon was heated, it was found that its heat stability was strong. The heat stability of PI in the Chinese strain C^'s cocoon and Japanese strain J^'s cocoon were stronger, and weaker relatively in the European strain Luo ni 9 hao's and polyvoltine strain Si hai's.