Interactions of barley α-amylase isozymes with Ca2 + , substrates and proteinaceous inhibitors

Autor: Morten T. Jensen, X. Robert, Birgit Christine Bønsager, Nathalie Juge, Birte Svensson, S. Tranier, Richard Haser, Jane Nøhr, Martin Willemoës, M. Abou Hachem, Nushin Aghajari, Birte Kramhøft, Sophie Bozonnet, Kenji Fukuda
Rok vydání: 2006
Předmět:
Zdroj: Biocatalysis and Biotransformation. 24:83-93
ISSN: 1029-2446
1024-2422
DOI: 10.1080/10242420500516163
Popis: α-Amylases are endo-acting retaining enzymes of glycoside hydrolase family 13 with a catalytic (β/α)8-domain containing an inserted loop referred to as domain B and a C-terminal anti-parallel β-sheet termed domain C. New insights integrate the roles of Ca2 + , different substrates, and proteinaceous inhibitors for α-amylases. Isozyme specific effects of Ca2 + on the 80% sequence identical barley α-amylases AMY1 and AMY2 are not obvious from the two crystal structures, containing three superimposable Ca2 + with identical ligands. A fully hydrated fourth Ca2 + at the interface of the AMY2/barley α-amylase/subtilisin inhibitor (BASI) complex interacts with catalytic groups in AMY2, and Ca2 + occupies an identical position in AMY1 with thiomaltotetraose bound at two surface sites. EDTA-treatment, DSC, and activity assays indicate that AMY1 has the highest affinity for Ca2 + . Subsite mapping has revealed that AMY1 has ten functional subsites which can be modified by means protein engineering to modulate t...
Databáze: OpenAIRE
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