Isolation and characterization of a soluble and thermostable phosphite dehydrogenase from Ralstonia sp. strain 4506(ENZYMOLOGY, PROTEIN ENGINEERING, AND ENZYME TECHNOLOGY)

概要

論文の詳細を見る
Phosphite dehydrogenase (PtxD), which catalyzes the nearly irreversible oxidation of phosphite to phosphate with the concomitant reduction of NAD^+ to NADH, has great potential for NADH regeneration in industrial biocatalysts. Here, we isolated a soil bacterium, Ralstonia sp. strain 4506, that grew at 45℃ on a minimal medium containing phosphite as the sole source of phosphorus. A recombinant PtxD of Ralstonia sp. (PtxD_<R4506>) appeared in the soluble fraction in Escherlchia coil. The purified PtxD_<R4506> showed 6.7-fold greater catalytic efficiency (V_<max>/K_m) than the first characterized PtxD of Pseudomonas stutzeri (PtxD_<PS>). Moreover, the purified PtxD_<R4506> showed maximum activity at 50℃, and its half-life of thermal inactivation at 45℃ was 80.5 h, which is approximately 3,450-fold greater than that of PtxD_<PS>. Therefore, we concluded that PtxD_<R4506>, which shows high catalytic efficiency, solubility, and thermostability, would be useful for NADH regeneration applications.
公益社団法人日本生物工学会の論文