| Autor: |
Long-Liu Lin, Jai-Shin Liu, Wen-Ching Wang, Szu-Han Chen, Chih-Chen Huang, Huei-Fen Lo |
| Předmět: |
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| Zdroj: |
World Journal of Microbiology & Biotechnology; May2008, Vol. 24 Issue 5, p619-626, 8p |
| Abstrakt: |
Abstract The functional and structural significance of glutamic acid 219 of a N- and C-terminally truncated Bacillus sp. strain TS-23 α-amylase (BACΔNC) was explored by the approach of site-directed saturation mutagenesis. The expressed wild-type and mutant enzymes have been purified by nickel-chelate chromatography and their molecular mass was determined to be approximately 54 kDa by SDS/PAGE. Except E219F, E219P, and E219W, all other mutant enzymes exhibited a lower shift in their optimum temperatures with respect to the wild-type enzyme. A decreased thermostability was also found in all of the mutant enzymes when compared with the wild-type form of BACΔNC. Except E219F, E219P, and E219W mutant enzymes, greater than 2-fold decrease in k cat and a similar substrate affinity relative to the wild-type BACΔNC were observed for the rest mutant enzymes. Based on these observations, it is suggested that Glu-219 apparently plays an important role in the thermostability of BACΔNC. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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