employed in the following examples for the confirmation of the reaction products and the measurement of yields thereof the preparation of the immobilized enzyme and the reaction were conducted in the same manner as in example 1 with the exception that the quantity of thermoase and that of the calcium acetate monohydrate were 9 0 g and 0 45 g respectively the quantity of the 0 05 m sodium acetate buffer solution of ph 7 5 was 90 ml the acrylic ester matrix carrier amberlite xad 7 trademark was replaced with 16 6 g of another carrier of the similar class amberlite xad 8 trademark containing about 150 wt of water on a dry basis the quantity of n benzyloxycarbonyl l aspartic acid was 2 14 g 8 m mol l phenylalanine methyl ester was replaced with 2 87 g 16 m mol of dl phenylalanine methyl ester the quantity of the water saturated ethyl acetate solution was changed to 26 ml and the reaction time was five fours n benzyloxycarbonyl l aspartyl l phenylalanine methyl ester was obtained in the yield of 79 8 the enzyme quantity carried on the immobilized enzyme prepared and used in this example was about 6 g the water content thereof was almost the same as the initial water content of the carrier the preparation of the immobilized enzyme and the reaction were carried out in the same manner as in example 2 with the exception that in place of the ethyl acetate solution employed in example 2 50 ml of water saturated methyl isobutyl ketone was used the reaction time was 3 hours and the washing of the immobilized enzyme after completion of the reaction was carried out with methyl isobutyl ketone n benzyloxycarbonyl l aspartyl l.