Details

Autor(en) / Beteiligte

• Kim, H.-J
• Kim, J.-H
• Oh, H.-J
• Oh, D.-K

Titel

Characterization of a mutated Geobacillus stearothermophilus l-arabinose isomerase that increases the production rate of d-tagatose

Ist Teil von

• Journal of applied microbiology, 2006-07, Vol.101 (1), p.213-221

Ort / Verlag

Oxford: Oxford, UK : Blackwell Publishing Ltd

Erscheinungsjahr

2006

Quelle

MEDLINE

Beschreibungen/Notizen

• Characterization of a mutated Geobacillus stearothermophilus [smallcapital l]-arabinose isomerase used to increase the production rate of [smallcapital d]-tagatose. A mutated gene was obtained by an error-prone polymerase chain reaction using [smallcapital l]-arabinose isomerase gene from G. stearothermophilus as a template and the gene was expressed in Escherichia coli. The expressed mutated [smallcapital l]-arabinose isomerase exhibited the change of three amino acids (Met³²²[rightward arrow]Val, Ser³⁹³[rightward arrow]Thr, and Val⁴⁰⁸[rightward arrow]Ala), compared with the wild-type enzyme and was then purified to homogeneity. The mutated enzyme had a maximum galactose isomerization activity at pH 8·0, 65°C, and 1·0 mM Co²⁺, while the wild-type enzyme had a maximum activity at pH 8·0, 60°C, and 1·0-mM Mn²⁺. The mutated [smallcapital l]-arabinose isomerase exhibited increases in [smallcapital d]-galactose isomerization activity, optimum temperature, catalytic efficiency (kcat/Km) for [smallcapital d]-galactose, and the production rate of [smallcapital d]-tagatose from [smallcapital d]-galactose. The mutated [smallcapital l]-arabinose isomerase from G. stearothermophilus is valuable for the commercial production of [smallcapital d]-tagatose. This work contributes knowledge on the characterization of a mutated [smallcapital l]-arabinose isomerase, and allows an increased production rate for [smallcapital d]-tagatose from [smallcapital d]-galactose using the mutated enzyme.