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Title: Role of several key residues in the catalytic activity of sucrose isomerase from Klebsiella pneumoniae NK33-98-8
Authors: Amornrat Aroonnual
Takuya Nihira
Tatsuji Seki
Watanalai Panbangred
Mahidol University
Osaka University
Keywords: Biochemistry, Genetics and Molecular Biology;Immunology and Microbiology
Issue Date: 3-Apr-2007
Citation: Enzyme and Microbial Technology. Vol.40, No.5 (2007), 1221-1227
Abstract: The gene encoding sucrose isomerase (palI NK33) was cloned from Klebsiella pneumoniae strain NK33-98-8. The gene was over-expressed in Escherichia coli BL21 (DE3) pLysS and its enzyme product (PalI NK33) was purified and characterized. PalI NK33 converts sucrose to 76.8% palatinose, 21.2% trehalulose and 1% each of glucose and fructose. The purified PalI NK33 showed the very high specific activity at 2362 U/mg and Kmfor sucrose was 42.7 ± 0.75 mM (at pH 6.0 and 30 °C). The enzyme activity was completely inhibited by 1 mM concentration of either Hg2+or SDS. Ca2+, Li2+and Mg2+at 1 mM slightly enhanced enzyme activity. Mutations on Asp140, located within the conserved sequence region I to either glutamic acid, glycine or asparagine had drastically reduced enzyme activity. The change of amino acid residues in the sequence325RLDRD329to325RYDRA329reduced enzyme activity 24-fold and did not affect ratio of palatinose and trehalulose formation. © 2006 Elsevier Inc. All rights reserved.
ISSN: 01410229
Appears in Collections:Scopus 2006-2010

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