抄録
L-Glutamic acid was formed from D-, L-, and DL-PCA with Cell-free extract of Pseudomonas alcaligenes ATCC-12815 grown in the medium containing DL-PCA as a sole source of carbon and nitrogen. The enzyme(s) involved in this conversion reaction was distributed in the soluble fraction within the cell and in 0.5 saturated fraction at the fractionation procedure with the saturation of ammonium sulfate. Optimum pH of this enzyme(s) lied at pH 8.5 and optimum temperature was 30°C. Cu (5×10-3M) inhibited the reaction considerably while Ca or Fe accelerated it. PALP (1×10-3M) also gave an enhanced activity to some extent. The enzyme preparation converted dextro-rotatory enanthiomorph of PCA to its laevo-rotatory one which in turn was not converted to the opposite rotation direction by this enzyme. Furthermore, the preparation did not, if any, show D-glutamic acid racemase activity. Isotopic experiments with using DL-PCA-1-14C revealed that L-glutamic acid-1-14C was formed by the cleavage of -CO-NH- bond of pyrrolidone ring of PCA. It was concluded that DL-PCA when assimilated by the present bacterium is at first transformed to L-PCA by the optically isomerizing enzyme and subsequently is cleaved to L-glutamic acid probably by the PCA hydrolysing enzyme.
