[Purification and some properties of D-hydantoinase produced by Pseudomonas 2262]

A D-hydantoinase produced by Pseudomonas 2262 was purified to electrophoretic homogeneity by the steps of thermal treatment, (NH4)2SO4 fractionation and column chromatography with Q-Sepharose fast flow, phenyl-Sepharose fast flow and Superose 12. Purification of about 60 fold was achieved with an overall yield of 16%. The relative molecular mass of the native enzyme is 109 kD and that of subunit is 53.7 kD by the analysis of Native and SDS-PAGE as well as gel filtration respectively. Some properties of the enzyme such as the sensitivity to thiol reagent and the effects of metal ions, for instance inhibited by Zn2+ and activited by Mn2+, Mg2+ are identical to dihydropyrimidinase. The optimum temperature and pH for enzymatic catalysis are 70 degrees C and 8.0 respectively. The enzyme activity is stable under 60 degrees C and in the pH range of 6-10. The N-terminal sequence for 10 amino acid residues is MDKLIKNGTI.