Enzymatic production of d-p-hydroxyphenylglycine from dl-5-p-hydroxyphenylhydantoin by Sinorhizobium morelens S-5

A microorganism with the ability to form d-p-hydroxyphenylglycine (d-pHPG) from dl-5-p-hydroxyphenylhydantoin (dl-5-pHPH) was isolated and identified as Sinorhizobium morelens S-5. Hydantoinase and carbamoylase involved in this bioconversion process were both strictly d-stereospecific. Addition of dl-5-(2-indolymethyl)hydantoin in the medium could enhance the biotransfromation ability of the cells of S. morelens S-5. The optimum temperature and pH for d-pHPG production, respectively, were 45 °C and 8.2 when resting cells were used during the biotransformation process. Partially purified d-carbamoylase exhibited a temperature optimum at 60 °C and pH optimum at 7.0 in 0.1 M phosphate buffer. The thermostablility of the enzyme was remarkable, with no loss of activity detected after 40 min at 50 °C.