title: Substrate specificity of the Bacillus licheniformis lyxose isomerase YdaE and its application in in vitro catalysis for bioproduction of lyxose and glucose by two-step isomerization.
abstract: Enzymatic processes are useful for industrially important sugar production, and in vitro two-step isomerization has proven to be an efficient process in utilizing readily available sugar sources. A hypothetical uncharacterized protein encoded by ydaE of Bacillus licheniformis was found to have broad substrate specificities and has shown high catalytic efficiency on D-lyxose, suggesting that the enzyme is D-lyxose isomerase. Escherichia coli BL21 expressing the recombinant protein, of 19.5 kDa, showed higher activity at 40 to 45°C and pH 7.5 to 8.0 in the presence of 1.0 mM Mn²+. The apparent K(m) values for D-lyxose and D-mannose were 30.4 ± 0.7 mM and 26 ± 0.8 mM, respectively. The catalytic efficiency (k(cat)/K(m)) for lyxose (3.2 ± 0.1 mM⁻¹ s⁻¹) was higher than that for D-mannose (1.6 mM⁻¹ s⁻¹). The purified protein was applied to the bioproduction of D-lyxose and D-glucose from d-xylose and D-mannose, respectively, along with the thermostable xylose isomerase of Thermus thermophilus HB08. From an initial concentration of 10 mM D-lyxose and D-mannose, 3.7 mM and 3.8 mM D-lyxose and D-glucose, respectively, were produced by two-step isomerization. This two-step isomerization is an easy method for in vitro catalysis and can be applied to industrial production.
authors.affiliation: Bio-energy Research Institute, Chonnam National University, Gwangju 500-757, Republic of Korea.
authors.forename: Darshan H
authors.initials: DH
authors.lastname: Patel
authors.forename: Seung Gon
authors.initials: SG
authors.lastname: Wi
authors.forename: Seong-Gene
authors.initials: SG
authors.lastname: Lee
authors.forename: Dae-Seok
authors.initials: DS
authors.lastname: Lee
authors.forename: Youn-ho
authors.initials: YH
authors.lastname: Song
authors.forename: Hyeun-Jong
authors.initials: HJ
authors.lastname: Bae
mesh_terms: D000595:Amino Acid Sequence; D001407:Bacillus / Q000201:enzymology* / Q000235:genetics; D003067:Coenzymes / Q000378:metabolism; D004795:Enzyme Stability; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D005947:Glucose / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007535:Isomerases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D008345:Manganese / Q000378:metabolism; D008358:Mannose / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010429:Pentoses / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity; D013696:Temperature; D016963:Thermus thermophilus / Q000201:enzymology; D014994:Xylose / Q000378:metabolism
chemical_list: D003067:Coenzymes; D010429:Pentoses; D011994:Recombinant Proteins; D008345:Manganese; C043333:lyxose; D014994:Xylose; D007535:Isomerases; D005947:Glucose; D008358:Mannose