title: Production of L-ribose from L-ribulose by a triple-site variant of mannose-6-phosphate isomerase from Geobacillus thermodenitrificans.
abstract: A triple-site variant (W17Q N90A L129F) of mannose-6-phosphate isomerase from Geobacillus thermodenitrificans was obtained by combining variants with residue substitutions at different positions after random and site-directed mutagenesis. The specific activity and catalytic efficiency (k(cat)/K(m)) for L-ribulose isomerization of this variant were 3.1- and 7.1-fold higher, respectively, than those of the wild-type enzyme at pH 7.0 and 70°C in the presence of 1 mM Co(2+). The triple-site variant produced 213 g/liter l-ribose from 300 g/liter L-ribulose for 60 min, with a volumetric productivity of 213 g liter(-1) h(-1), which was 4.5-fold higher than that of the wild-type enzyme. The k(cat)/K(m) and productivity of the triple-site variant were approximately 2-fold higher than those of the Thermus thermophilus R142N variant of mannose-6-phosphate isomerase, which exhibited the highest values previously reported.
authors.affiliation: Department of Bioscience and Biotechnology, Konkuk University, Seoul, Republic of Korea.
authors.forename: Yu-Ri
authors.initials: YR
authors.lastname: Lim
authors.forename: Soo-Jin
authors.initials: SJ
authors.lastname: Yeom
authors.forename: Deok-Kun
authors.initials: DK
authors.lastname: Oh
mesh_terms: D001709:Biotechnology / Q000379:methods; D004795:Enzyme Stability; D014644:Genetic Variation; D056506:Geobacillus / Q000201:enzymology* / Q000235:genetics; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008359:Mannose-6-Phosphate Isomerase / Q000235:genetics* / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D010429:Pentoses / Q000378:metabolism*; D012266:Ribose / Q000096:biosynthesis*
chemical_list: D010429:Pentoses; C100182:ribulose; D012266:Ribose; D008359:Mannose-6-Phosphate Isomerase