W. Xu, Wenli Zhang, Yuqing Tian
Feb 1, 2017
Citations
1
Influential Citations
19
Citations
Journal
Process Biochemistry
Abstract
Abstract d -Allose was considered as a kind of rare sugars with testified potential medicinal and agricultural benefits. l -Rhamnose isomerase (L-RI, EC 5.3.1.14), an aldose-ketose isomerase, played a significant part in producing rare sugar. In this article, a thermostable d -allose-producing L-RI was characterized from a thermotolerant bacterium, Thermobacillus composti KWC4. The recombinant L-RI was activated obviously in the presence of Mn2+ with an optimal pH 7.5 and temperature 65 °C. The Michaelis-Menten constant (Km), turnover number (kcat) and catalytic efficiency (kcat/Km) for l -rhamnose were 33.8 mM, 1189.8 min−1 and 35.2 min−1 mM−1, respectively. At a higher temperature, Mn2+ played a pivotal role in strengthening the thermostability of T. composti L-RI. The differential scanning calorimetry (DSC) results showed the denaturing temperature (Tm) of T. composti L-RI was increased by 3 °C in presence of Mn2+. Although the T. composti L-RI displayed the optimum substrate as l -rhamnose, it could also effectively catalyze the isomerization between d -allulose and d -allose. When the reaction reached equilibrium, the sole product d -allose was produced from D-alluose by T. composti L-RI.