Removal of the Four C-Terminal Glycine-Rich Repeats Enhances the Thermostability and Substrate Binding Affinity of Barley 
详细信息 查看全文
详细信息 查看全文
- 作者：Yue F. Ma ; Jason K. Eglinton ; D. Evan Evans ; Sue J. Logue ; and Peter Langridge
- 刊名：Biochemistry
- 出版年：2000
- 出版时间：November 7, 2000
- 年：2000
- 卷：39
- 期：44
- 页码：13350 - 13355
- 全文大小：196K
- 年卷期：v.39,no.44(November 7, 2000)
- ISSN：1520-4995
文摘
Barley 
-amylase undergoes proteolytic cleavage in the C-terminal region after germination.The implication of the cleavage in the enzyme's characteristics is unclear. With purified native -amylasesfrom both mature barley grain and germinated barley, we found that the -amylase from germinatedbarley had significantly higher thermostability and substrate binding affinity for starch than that frommature barley grain. To better understand the effect of the proteolytic cleavage on the enzyme'sthermostability and substrate binding affinity for starch, recombinant barley -amylases with specificdeletions at the C-terminal tail were generated. The complete deletion of the four C-terminal glycine-richrepeats significantly increased the enzyme's thermostability, but an incomplete deletion with one repeatremaining did not change the thermostability. Although different C-terminal deletions affect thethermostability differently, they all increased the enzyme's affinity for starch. The possible reasons forthe increased thermostability and substrate binding affinity, due to the removal of the four C-terminalglycine-rich repeats, are discussed in terms of the three-dimensional structure of -amylase.
-amylase undergoes proteolytic cleavage in the C-terminal region after germination.The implication of the cleavage in the enzyme's characteristics is unclear. With purified native -amylasesfrom both mature barley grain and germinated barley, we found that the -amylase from germinatedbarley had significantly higher thermostability and substrate binding affinity for starch than that frommature barley grain. To better understand the effect of the proteolytic cleavage on the enzyme'sthermostability and substrate binding affinity for starch, recombinant barley -amylases with specificdeletions at the C-terminal tail were generated. The complete deletion of the four C-terminal glycine-richrepeats significantly increased the enzyme's thermostability, but an incomplete deletion with one repeatremaining did not change the thermostability. Although different C-terminal deletions affect thethermostability differently, they all increased the enzyme's affinity for starch. The possible reasons forthe increased thermostability and substrate binding affinity, due to the removal of the four C-terminalglycine-rich repeats, are discussed in terms of the three-dimensional structure of -amylase.