PRODUCTION OF OPTICALLY-ACTIVE 3-PHENYLGLYCIDIC ACID ESTER BY THE LIPASE FROM SERRATIA-MARCESCENS ON A HOLLOW-FIBER MEMBRANE REACTOR

(+/-)-trans-3-(4-Methoxyphenyl)glycidic acid methyl ester [(+/-)-MPGM] , a key intermediate in the synthesis of diltiazem hydrochloride, was efficiently hydrolyzed by lipase from Serratia marcescens Sr41 8000 im mobilized on a hollow-fiber ultrafiltration membrane. The lipase was i mmobilized on a spongy layer of the shell side of the membrane by mean s of physical adsorption. Asymmetric hydrolysis was carried out semi-c ontinuously at 22-degrees-C in a membrane reactor circulating both tol uene solution containing (+/-)-MPGM in the shell loop and aqueous solu tion (pH 8.5) in the lumen loop. (+)-MPGM was hydrolyzed to (+)-(2S, 3 R)-3-(4-methoxyphenyl)glycidic acid and methanol. p-Methoxyphenylaceta ldehyde derived from the glycidic acid was accumulated in the toluene phase and inhibited the enzyme reaction. The inhibition, however, was suppressed by the addition of sodium hydrogen sulfite to the aqueous p hase, because the aldehyde and sodium hydrogen sulfite formed an adduc t and the adduct was transferred to the aqueous phase with the progres s of enzyme reaction. The lipase immobilized on the hydrophilic membra ne exhibited a high stability: the half-life of enzyme activity at 22- degrees-C was 127 h, which was about 30-fold that in the conventional emulsion reactor. The maximum value of the velocity constant (k(+)) fo r the hydrolysis of (+)-MPGM was 0.25 h-1 under the condition of immob ilization of 1.6 x 10(5) units of lipase per m2. Since reaction and pr oduct separation were achieved simultaneously, crystalline (-)-MPGM wi th a high yield of 40-43% and optical purity of 100% enantiomeric exce ss [e.e.] was obtained through six runs by concentration of the toluen e phase after the reaction.