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

Stacey M. Southall, Peter J. Simpson, Harry J. Gilbert, Gary Williamson, Michael P. Williamson

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130 Citations (Scopus)

Abstract

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. Copyright (C) 1999 Federation of European Biochemical Societies.

Original languageEnglish
Pages (from-to)58-60
Number of pages3
JournalFEBS Letters
Volume447
Issue number1
DOIs
Publication statusPublished - 19 Mar 1999
Externally publishedYes

Keywords

  • Aspergillus niger
  • Glucoamylase
  • Starch-binding domain

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