1989 Fiscal Year Final Research Report Summary
Study on Proteases and Their Inhibitors of the Silkworm
| Project/Area Number |
62480048
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
蚕糸学
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| Research Institution | Kyoto Institute of Technology |
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Principal Investigator |
EGUCHI Masaharu Kyoto Institute of Technology Faculty of Textile Science, Professor, 繊維学部, 教授 (00027856)
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| Co-Investigator(Kenkyū-buntansha) |
AZUMA Masaaki Tottori University, Department of Agriculture, Associate Professor, 農学部, 助教授 (20175871)
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| Project Period (FY) |
1987 – 1989
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| Keywords | Silkworm / Midgut / Protease / Muscardine Fungus / Protease Inhibitor / Chymo trypsin Inhibitor / Hemolymph / Integument |
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| Research Abstract |
In the larval midgut of the silkworm, the characteristic and associated form of trypsin and chymotrypsin-like tissue proteases were studied. These proteases were considered to be the tightly bound membrane bound enzymes. Immunochemical study showed that the chymotrypsin-like protease was synthesized as the 32K protein and associated with the membrane and converted into the 27K protein by the alkaline digestive fluid in the gut lumen. The trypsin-like protease was synthesized as the 42K protein and will change into a smaller protein by similar processing. The activity of these proteases increased steeply after hatching and by the administration of mulberry leaves.
Concerning protein protease inhibitors of the silkworm, the inhibitory effect was studied against proteases from Beauveria bassiana. A low molecular weight protease-F revealed the strong activity in the hemolymph and integument. The purified inhibitor-F from the hemolymph was found to inhibit the germ tube development of B. bassiana. Subsequently, we purified and characterized chymotrypsin inhibitors d, e and g from hemolymph and g from the fat body of the silkworm. In vitro experiment showed that the discharge of chymotrypsin inhibitors from the cultured fat body into the medium was stimulated by added ecdysterone. The electrophoresis after solubilization of the fat body suggested the conversion of the inhibitor g' into e in vivo. The inhibitor d was undiscernible in the fat body, but the immunoelectrophoresis suggested the presence of precursor of this inhibitor in the fat body.
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