Recombination and expression of a novel phosphosugar isomerase in E.coli

Ribose-5-phosphate isomerase B ( RpiB) is a main enzyme for biotransformation D-psicose to D-allose, a novel rare sugar.Ribose-5-phosphate isomerase B from Thermotoga lettingae TMO was cloned and expressed in Escherichia coli BL21 ( DE3) .The genetically engineered bacterium was induced by IPTG, then the recombinant RpiB was purified to electrophoretical homogeneity with affinity chromatography. The recombinant RpiB was analyzed by SDS- PAGE, and approximately 17ku target protein was observed on the SDS- PAGE. The activity assay of recombinant enzyme showed a relatively high enzyme activity of D- allose- producing. Conversion rates after 3h of resting cells and pure enzyme reaction were 19% and 23%, respectively.