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Removal of the four C-terminal glycine rich repeats enhances the thermostability of barley β-amylase

journal contribution
posted on 2023-05-16, 16:32 authored by Ma, YF, Eglinton, JK, Evans, E, Logue, SJ, Langridge, P
Barley β-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 β-amylases from both mature barley grain and germinated barley, we found that the β-amylase from germinated barley had significantly higher thermostability and substrate binding affinity for starch than that from mature barley grain. To better understand the effect of the proteolytic cleavage on the enzyme's thermostability and substrate binding affinity for starch, recombinant barley β-amylases with specific deletions at the C-terminal tail were generated. The complete deletion of the four C-terminal glycine-rich repeats significantly increased the enzyme's thermostability, but an incomplete deletion with one repeat remaining did not change the thermostability. Although different C-terminal deletions affect the thermostability differently, they all increased the enzyme's affinity for starch. The possible reasons for the increased thermostability and substrate binding affinity, due to the removal of the four C-terminal glycine-rich repeats, are discussed in terms of the three-dimensional structure of β-amylase.

History

Publication title

Biochemistry

Volume

39

Pagination

13350-13355

ISSN

0006-2960

Department/School

Tasmanian Institute of Agriculture (TIA)

Publisher

American Chemical Society

Place of publication

United States

Repository Status

  • Restricted

Socio-economic Objectives

Barley

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