The starch‐binding domain from glucoamylase disrupts the structure of starch

FEBS Letters

Southall, Stacey M.³  Gilbert, Harry J.¹  Simpson, Peter J.³  Williamson, Michael P.³  Williamson, Gary² 

[1] Department of Biological and Nutritional Sciences, University of Newcastle upon Tyne, Newcastle upon Tyne NE1 7RU, UK;Institute of Food Research, Norwich Research Park, Colney, Norwich NR4 7UA, UK;Department of Molecular Biology and Biotechnology, Krebs Institute, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2UH, UK

关键词: Starch-binding domain;    Glucoamylase;    Aspergillus niger;   

DOI  :  10.1016/S0014-5793(99)00263-X

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The full-length glucoamylase from Aspergillus niger, G1, consists of an N-terminal catalytic domain followed by a semi-rigid linker (which together constitute the G2 form) and a C-terminal starch-binding domain (SBD). G1 and G2 both liberate glucose from insoluble corn starch, although G2 has a rate 80 times slower than G1. Following pre-incubation of the starch with SBD, the activity of G1 is uniformly reduced with increasing concentrations of SBD because of competition for binding sites. However, increasing concentrations of SBD produce an initial increase in the catalytic rate of G2, followed by a decrease at higher SBD concentrations. The results show that SBD has two functions: it binds to the starch, but it also disrupts the surface, thereby enhancing the amylolytic rate.

【 授权许可】

Unknown