CHEMOENZYMATIC SYNTHESIS OF D(-)PHENYLGLYCINE USING HYDANTOINASE OF PSEUDOMONAS-DESMOLYTICUM RESTING CELLS

We screened 125 Pseudomonas strains from our culture collection for th e production of hydantoinase activity using DL-phenylhydantoin as a su bstrate. Pseudomonas desmolyticum NCIM 2112 was Sound to be the best h ydantoinase (dihydropyrimidinase E.C. 3.5.2.2) producer. The enzymatic reactions were carried out using 18-20-h grown cells in nutrient brot h and 5-phenylhydantoin as the substrate. Optimization studies Sor the biotransformation reaction were performed to increase product yield. The optimum pH and temperature for D(-)N-carbamoylphenylglycine produc tion were 9.5 and 30 degrees C, respectively. Biotransformation under these alkaline conditions allowed the complete conversion of 27.0 g l( -1) of DL-phenylhydantoin to 26.5 g 1(-1) of N-carbamoylphenylglycine within 24 h, with a molar yield of 90%. The hydantoinase involved in t his biotransformation process was strictly D-stereospecific, because t he product isolated was pure D(-)N-carbamoylphenylglycine. This pure p roduct was further chemically converted to D(-)phenylglycine using nit rous acid with an 80% chemical yield. Thus, the overall conversion eff iciency of DL-5-phenylhydantoin to D(-)phenylglycine was Sound to be 6 5-68%.