An enzyme membrane system was constructed by immobilizing trypsin onto chitin and ultrafiltration set-up was employed to investigate the activity of thus prepared enzyme membranes. Benzoylarginine ethyl ester (BAEE) and casein were used as substrates. Using BAEE as a substrate, the dependence of conversion on pH was examined under flow condition (ultrafiltration). The results showed that the optimum pH for the enzyme membrane was shifted from 7.8 for native enzyme toward more alkaline pH 9.0. The shift was assumed to be caused by the localized high concentration of enzyme molecules and of the released carboxylic acids during the hydrolysis of substrate. In order to measure the "figure of merit" the reaction rates with a membrane were measured under the flow and batch conditions. The rates were calculated from the conversions of substrate, when the conversions for both flow and batch conditions were equal. The results obtained with BAEE as a substrate gave the figure of merit 5.67, indicating that reaction rate for flow system was five times larger than that for batch system. This result implies that in the forced flow of substrate solution through an enzyme membrane, diffusion limitations could be eliminated by exposing all the enzyme molecules in the membrane to incoming substrate molecules. When casein, a high molecular weight substate, was used this tendency was expected to be more pronounced. In the case of casein conversion was expressed by total uv absorption (△E) and the figure of merit was determined by comparing the time periods required to reach the same uv absorption, i.e., the same extent of reaction. The results showed that the figure of merit was 10.3, and then figure of merit for casein was two times larger than that for BAEE.

키틴 막에 trypsin을 immobilize 해서 효소막을 제조하고 ultrafiltration 기구를 사용하여 이 효스막의 activity를 측정하였다. Benzoylarginine ethyl ester (BAEE)와 casein이 기질로 사용되었다. BAEE를 기질로 해서 flow condition 하에서 pH 대한 영향을 조사하였다. 그 결과 최대의 activity를 보여주는 pH가 자연상태의 trypsin의 최적 pH 7.8보다 휠씬 염기성 쪽인 pH 9.0으로 옮겨갔다. 이러한 최적 pH의 이동은 효소가 이 효소막 내부에 높은 농도로 모여있고 또 분해 반응중에 생성되는 carboxylic acid에 의한 것이다. "Figure of merit"를 측정하기 위해서 이 효소막을 이용해서 flow와 batch condition의 두 조건하에서 각각 activity를 측정하였다. 이 두 조건하에서 conversion이 같게 되었을 때를 찾아 그때의 반응속도를 비교하는 방법으로 "figure of merit"를 결정하였다. BAEE를 기질로 사용하였을 때 figure of merit는 5.67이었다. 이것은 flow system이 batch system보다 다섯배 이상의 높은 activity를 보여준다는 것을 뜻한다. 이 결과로부터 flow condition하에서 diffusion Limitation이 많이 제거되어졌음이 밝혀졌다. Casein을 기질로 사용하였을 때는 figure of merit가 10.3으로 나타나 큰 분자량을 가진 물질을 기질로 하였을 경우 diffusion limitation 문제가 더 심각함을 알 수 있었다.

Keywords: