Characterization of a mannose-6-phosphate isomerase from Geobacillus thermodenitrificans that converts monosaccharides

2009 ◽  
Vol 31 (8) ◽  
pp. 1273-1278 ◽  
Author(s):  
Soo-Jin Yeom ◽  
Nam-Hee Kim ◽  
Ran-Young Yoon ◽  
Hyun-Jung Kwon ◽  
Chang-Su Park ◽  
...  
Keyword(s):  
Geobacillus Thermodenitrificans ◽  
Mannose 6 Phosphate

scholarly journals Characterization of a Mannose-6-Phosphate Isomerase fromThermus thermophilusand Increased l-Ribose Production by Its R142N Mutant

2010 ◽  
Vol 77 (3) ◽  
pp. 762-767 ◽  
Author(s):  
Soo-Jin Yeom ◽  
Eun-Sun Seo ◽  
Bi-Na Kim ◽  
Yeong-Su Kim ◽  
Deok-Kun Oh
Keyword(s):  
Specific Activity ◽  
Thermus Thermophilus ◽  
Catalytic Efficiency ◽  
Maximal Activity ◽  
Wild Type ◽  
Active Site Residues ◽  
Geobacillus Thermodenitrificans ◽  
Wild Type Enzyme ◽  
Mannose 6 Phosphate

ABSTRACTAn uncharacterized gene fromThermus thermophilus, thought to encode a mannose-6-phosphate isomerase, was cloned and expressed inEscherichia coli. The maximal activity of the recombinant enzyme forl-ribulose isomerization was observed at pH 7.0 and 75°C in the presence of 0.5 mM Cu2+. Among all of the pentoses and hexoses evaluated, the enzyme exhibited the highest activity for the conversion ofl-ribulose tol-ribose, a potential starting material for manyl-nucleoside-based pharmaceutical compounds. The active-site residues, predicted according to a homology-based model, were separately replaced with Ala. The residue at position 142 was correlated with an increase inl-ribulose isomerization activity. The R142N mutant showed the highest activity among mutants modified with Ala, Glu, Tyr, Lys, Asn, or Gln. The specific activity and catalytic efficiency (kcat/Km) forl-ribulose using the R142N mutant were 1.4- and 1.6-fold higher than those of the wild-type enzyme, respectively. Thekcat/Kmof the R142N mutant was 3.8-fold higher than that ofGeobacillus thermodenitrificansmannose-6-phosphate isomerase, which exhibited the highest activity to date for the previously reportedkcat/Km. The R142N mutant enzyme produced 213 g/literl-ribose from 300 g/literl-ribulose for 2 h, with a volumetric productivity of 107 g liter−1h−1, which was 1.5-fold higher than that of the wild-type enzyme.

scholarly journals Production of l-Ribose from l-Ribulose by a Triple-Site Variant of Mannose-6-Phosphate Isomerase from Geobacillus thermodenitrificans

2012 ◽  
Vol 78 (11) ◽  
pp. 3880-3884 ◽  
Author(s):  
Yu-Ri Lim ◽  
Soo-Jin Yeom ◽  
Deok-Kun Oh
Keyword(s):  
Specific Activity ◽  
Thermus Thermophilus ◽  
Catalytic Efficiency ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Wild Type ◽  
Geobacillus Thermodenitrificans ◽  
Wild Type Enzyme ◽  
Content Type ◽  
Mannose 6 Phosphate

ABSTRACTA triple-site variant (W17Q N90A L129F) of mannose-6-phosphate isomerase fromGeobacillus thermodenitrificanswas obtained by combining variants with residue substitutions at different positions after random and site-directed mutagenesis. The specific activity and catalytic efficiency (kcat/Km) forl-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 Co2+. The triple-site variant produced 213 g/literl-ribose from 300 g/literl-ribulose for 60 min, with a volumetric productivity of 213 g liter−1h−1, which was 4.5-fold higher than that of the wild-type enzyme. Thekcat/Kmand productivity of the triple-site variant were approximately 2-fold higher than those of theThermus thermophilusR142N variant of mannose-6-phosphate isomerase, which exhibited the highest values previously reported.

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