| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1986: ¥200,000 (Direct Cost: ¥200,000)
Fiscal Year 1985: ¥1,600,000 (Direct Cost: ¥1,600,000)
|
|---|
| Research Abstract |
Streptomyces subtilisin inhibitor (abbreviated as SSI) is a proteinaceous inhibitor of subtilisin BPN', a bacterial serine proteinase. Structures of SSI and a complex of SSI-subtilisin BPN' have been elucidated; SSI is bound to the enzyme in the similar fashion as is a good substrate. However, for some reasons, which we would very much like to know, the catalytic action of the proteinase does not take place in this complex under the ordinary conditions, hence SSI is an inhibitor. On the other hand, in a narrow range of acidic pH, the enzymic catalysis takes place in the complex of SSI-subtilisin BPN', and we can isolate a molecular species of SSI in which the peptide bond between Met 73 and Val 74 is cleaved, a product of the enzyme reaction (called the modified SSI, and abbreviated as <SSI^*> ). In this study we established the conditions for producing <SSI^*> efficiently from the complex of SSI-subtilisin BPN', and made some kinetic analysis of the process of <SSI^*> release. <SSI^*> thus prepared inhibits subtilisin BPN' still strongly, though less than SSI, and a stable complex of <SSI^*> -subtilisin BPN' can be obtained. SSI and <SSI^*> are unique subjects not only for the study of structure= function relationship of a globular protein, but also for the study of reaction mechanism of a proteinase. Some structural propertiesof <SSI^*> and some kinetic features of <SSI^*> -subtilisin BPN' interaction were compared with those of native SSI also in thid study.
|
