Isolation and characterization of an extremely thermostable D-xylose isomerase from Thermus aquaticus HB 8

Abstract

The extremely &hemophilic organism Thermus quaticus possesses high activities of enzymes catalysing the degradation of xyians and metabolizing ~x y l o s e via the pntose phosphate pathway. The D-xylsse isomerase (Dxylsse ketoll-isomerase, EC 5 o 3 o I . 51, an important enzyme of this process, is efficiently induced by its substrate Dxylose, and, 40 a lesser extent, by related pentoses and some derivatives of 1p-xylose. The ~-xyPose isomerase from T. qrsatkus has been g u~e d by anion-exchange chrmmtography, chromatography on ID-xylkose agarose and gcE filtration. A single band migrating according to an Mr of 5 0 0 was obtained by SDS-PAGE. An M,. oh 194800 for the native enzyme, determined by gel filtration and ultracentrifugation in a glycerol gradient, suggested that the Dxylsw isomerase is a homomeric tetramer. Amhenius plots of the enzyme activity of the D-xylose isomerase weref linear up to a temperature of $5 OC. At 90 "C the enzyme was inactivated in the absence of divalent c;~PPoRs, with a haIf4ife of 4 d, while in the presence of Mn2+ or Co2+ it remained fully active for at least 1 mo~ith. The enzyme $ilia2 an isoelectric point at 4.4 and showed a broad optimum in the pH range from 5-5 to 8-5. NQ significant difkepemces in the pH and temperature behaviour could be observed when ~x y l o s e was compared with D -~~U C Q W as substrate. Digearen& methods of immobilization of the enzyme to solid supports as well as inclusion into nyhm beads w m studied. Attachment of the enzyme to epoxy-activated agarose and its m-aggregation with bovine serum albumin gave immobilized preparations with the same stability as free enzyme supplemente i t h hh2+ QP cQ*+e

Purification and Characterization ofD-Xylose Isomerase fromBifidobacterium adolescentis

“…Most of the microbial o-xylose isomerases with molecular weights of 140,000-200,000 are composed of four identical subunits, but 0-xylose isomerase of alkalophilic Bacillus has been reported to have three subunits. 13 )The isoelectric point of the enzyme was about 4.3 by isoe1ectric focusing, which is close to those of the enzyme from Thermus aquaticus 14 ) and an alkalophilic Bacillus. 15) …”

Efficient production of thermostable Thermus thermophilus xylose isomerase in Escherichia coli and Bacillus brevis

“…Here we have shown that B. brevis is also suitable for the production of intracellular protein, even if the gene is quite different from the usual Bacillus genes. Lehmacher and Bisswanger (1990) recently purified and characterized a xylose isomerase from Thermus thermophilus HB8. However, their data, e.g.…”

Glikoz İzomeraz Üreticisi Dört Geobacillus Suşunun İzolasyonu ve Moleküler Metotlar Kullanarak Tanımlanması

“…Thermoanaerobacterium sp. (Liu vd., 1996), Lactobacillus brevis (Yamanaka, 1975), Thermus aquaticus (Lehmbacher, 1990), Anoxybacillus gonensis (Karaoğlu vd., 2013) glikoz izomerazları haricindeki diğer glikoz izomerazların optimum pH değeri 6.5'ten yukarıdır. Streptomyces sp., T. thermophilus ve Clostridium thermosulfurogenes'ten elde edilen glikoz izomerazların optimum pH'ları 7.0'dir (Karaoğlu vd., 2013).…”