Glucoamylase: structure/function relationships, and protein engineering

Jørgen Sauer, Bent W. Sigurskjold, Ulla Christensen, Torben P. Frandsen, Ekaterina Mirgorodskaya, Matt Harrison, Peter Roepsdorff, Birte Svensson

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Glucoamylases are inverting exo-acting starch hydrolases releasing beta-glucose from the non-reducing ends of starch and related substrates. The majority of glucoamylases are multidomain enzymes consisting of a catalytic domain connected to a starch-binding domain by an O-glycosylated linker region. Three-dimensional structures have been determined of free and inhibitor complexed glucoamylases from Aspergillus awamori var. X100, Aspergillus niger, and Saccharomycopsis fibuligera. The catalytic domain folds as a twisted (alpha/alpha)(6)-barrel with a central funnel-shaped active site, while the starch-binding domain folds as an antiparallel beta-barrel and has two binding sites for starch or beta-cyclodextrin. Certain glucoamylases are widely applied industrially in the manufacture of glucose and fructose syrups. For more than a decade mutational investigations of glucoamylase have addressed fundamental structure/function relationships in the binding and catalytic mechanisms. In parallel, issues of relevance for application have been pursued using protein engineering to improve the industrial properties. The present review focuses on recent findings on the catalytic site, mechanism of action, substrate recognition, the linker region, the multidomain architecture, the engineering of specificity and stability, and roles of individual substrate binding subsites.
Original languageEnglish
JournalBBA General Subjects
Volume1543
Issue number2
Pages (from-to)275-293
ISSN0304-4165
DOIs
Publication statusPublished - 2000
Externally publishedYes

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