1993 Fiscal Year Final Research Report Summary
Improvement of enzymes by radom mutagenesis
| Project/Area Number |
04650875
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
発酵工学
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| Research Institution | Osaka University |
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Principal Investigator |
URABE Itaru Osaka Univ. Dept. of Bioeg., Prof., 工学部, 教授 (60029246)
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| Co-Investigator(Kenkyū-buntansha) |
YOMO Tetsuya Osaka Univ. Dept. of Bioeg., Assist. Prof., 工学部, 助手 (00222399)
NEGORO Seiji Osaka Univ. Dept. of Bioeg., Assist. Prof., 工学部, 助教授 (90156159)
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| Project Period (FY) |
1992 – 1993
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| Keywords | 酵素の改良 / タンパク質工学 / ランダム変異 / 配列空間 / B.stearothermophilus / ペルオキシダーゼ |
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| Research Abstract |
a landscape in protein sequence space shows th reiationship between the primary structure and the level of a property of each protein. We developed methods for observing local Iands capes experimentally through catalase I from Bacillus stearothermophilus with respect to its catalatic activity, peroxidatic activity, and thermostability. The enzyme gene was randomly mutated and a mutant library composing of 2648 transformants was obtained. Based on the activity and productivity of these transformants, 82 were selected as a sample group for measuring the altitude of catalase I.The altitude of the wild-type enzyme is close to the highest level in the mutant population for the termostability landscape, but is at theaverage level for the peroxidatic activit. as for the catalytic activity, its altitude lies in between the two positions. A positive correlation was found between the altitude of the catalatic and the peroxidatic activities, indicating that the location of the hills and valleys in he landscapes of the two activities roughly correspond with each other. In contrast, the thermostability landscape appeared quite differently. The smoothness of the landscape was examined through the number of mutations in the structural geves of the mutant enzymes of different properties. The correlation beween the number of mutations and the level of each property showed that the thermoxtability landscape is smooth. but not with the two activity landscapes. Thus, the results show that even form a rough sketch of the landcapes based on the experimental data, the characteristic features of catalase I can be elucidated. The sketch of landscape, therefore, probides a new view in understanding enzymes.
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