title: Substrate specificity of a recombinant D-lyxose isomerase from Providencia stuartii for monosaccharides.
abstract: The specific activity and catalytic efficiency (k(cat)/K(m)) of the recombinant putative protein from Providencia stuartii was the highest for D-lyxose among the aldose substrates, indicating that it is a D-lyxose isomerase. Gel filtration analysis suggested that the native enzyme is a dimer with a molecular mass of 44 kDa. The maximal activity for D-lyxose isomerization was observed at pH 7.5 and 45 degrees C in the presence of 1 mM Mn(2+). The enzyme exhibited high isomerization activity for aldose substrates with the C2 and C3 hydroxyl groups in the left-hand configuration, such as D-lyxose, D-mannose, L-ribose, D-talose, and L-allose (listed in decreasing order of activity). The enzyme exhibited the highest activity for D-xylulose among all pentoses and hexoses. Thus, D-lyxose was produced at 288 g/l from 500 g/l D-xylulose by D-lyxose isomerase at pH 7.5 and 45 degrees C for 2 h, with a conversion yield of 58% and a volumetric productivity of 144 g l(-1) h(-1). The observed k(cat)/K(m) (920 mM(-1) s(-1)) of P. stuartiid-lyxose isomerase for D-xylulose is higher than any of the k(cat)/K(m) values previously reported for sugar and sugar phosphate isomerases with monosaccharide substrates. These results suggest that the enzyme will be useful as an industrial producer of D-lyxose.
authors.affiliation: Department of Bioscience and Biotechnology, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701, Republic of Korea. deokkun@konkuk.ac.kr
authors.forename: Hyun-Jung
authors.initials: HJ
authors.lastname: Kwon
authors.forename: Soo-Jin
authors.initials: SJ
authors.lastname: Yeom
authors.forename: Chang-Su
authors.initials: CS
authors.lastname: Park
authors.forename: Deok-Kun
authors.initials: DK
authors.lastname: Oh
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D003001:Cloning, Molecular; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004926:Escherichia coli / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D007535:Isomerases / Q000235:genetics* / Q000378:metabolism*; D008670:Metals / Q000494:pharmacology; D009005:Monosaccharides / Q000378:metabolism*; D010429:Pentoses / Q000378:metabolism; D011532:Providencia / Q000201:enzymology* / Q000235:genetics; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D004791:Enzyme Inhibitors; D008670:Metals; D009005:Monosaccharides; D010429:Pentoses; D011994:Recombinant Proteins; C043333:lyxose; D007535:Isomerases