title: Direct production of D-arabinose from D-xylose by a coupling reaction using D-xylose isomerase, D-tagatose 3-epimerase and D-arabinose isomerase.
abstract: Klebsiella pneumoniae 40bXX, a mutant strain that constitutively produces D-arabinose isomerase (D-AI), was isolated through a series of repeated subcultures from the parent strain on a mineral salt medium supplemented with L-Xylose as the sole carbon source. D-AI could be efficiently immobilized on chitopearl beads. The optimum temperature for the activity of the immobilized enzyme was 40 degrees C and the enzyme was stable up to 50 degrees C. The D-Al was active at pH 10.0 and was stable in the range of pH 6.0-11.0. The enzyme required manganese ions for maximum activity. Three immobilized enzymes, D-xylose isomerase (D-XI), D-tagatose 3-epimerase (D-TE and D-AI were used for the preparation of D-arabinose from D-xylose in a coupling reaction. After completion of the reaction, degradation of D-xylulose was carried out by Saccharomyces cerevisiae. The reaction mixture containing D-Xylose, D-ribulose and the product was then separated by ion exchange column chromatography. After crystallization, the product was checked by HPLC, IR spectroscopy, NMR spectroscopy and optical rotation measurements. Finally, 2.0 g of D-arabinose could be obtained from 5 g of the substrate.
authors.affiliation: Department of Biochemistry and Food Science, Faculty of Agriculture, Kagawa University, Kagawa 761-0795, Japan.
authors.forename: Ishrat
authors.initials: I
authors.lastname: Sultana
authors.forename: Rahman Md
authors.initials: RM
authors.lastname: Mizanur
authors.forename: Kei
authors.initials: K
authors.lastname: Takeshita
authors.forename: Goro
authors.initials: G
authors.lastname: Takada
authors.forename: Ken
authors.initials: K
authors.lastname: Izumori