Goldman R, Silman H I, Caplan S R, Kedem O, Katchalski E
Science. 1965 Nov 5;150(3697):758-60. doi: 10.1126/science.150.3697.758.
A stable papain membrane has been prepared on a collodion matrix by absorbing papain in a collodion membrane and then cross-linking the papain with bisdiazobenzidine 3,3'-disulfonic acid. The pH-dependence of the activity of the enzyme membrane on the low-molecular-weight substrate, benzoylarginine ethyl ester, was found to differ from that of crystalline papain; the activity was low in the neutral pH range where the native enzyme has its optimum and high at alkaline pH. This anomalous behavior is due to a lowering of the local pH within the membrane as a result of the release of acid by the enzymic hydrolysis of the ester substrate.
通过将木瓜蛋白酶吸附在火棉胶膜中，然后用3,3'-二磺酸重氮苯交联木瓜蛋白酶，在火棉胶基质上制备了一种稳定的木瓜蛋白酶膜。发现该酶膜对低分子量底物苯甲酰精氨酸乙酯的活性的pH依赖性与结晶木瓜蛋白酶不同；在天然酶具有最佳活性的中性pH范围内活性较低，而在碱性pH下活性较高。这种异常行为是由于酯底物的酶促水解释放酸导致膜内局部pH降低所致。
