天然タンパク質の加水分解による生理活性ペプチドの新しい抽出合成法

在这项研究中，我们的目标是(1)利用酶催化玉米蛋白(Zeins)的水解来控制所需多肽(如血管紧张素转换酶(ACE)抑制肽)的选择性生产；(2)开发在有机介质中具有催化活性的酶制剂。主要研究结果如下：1.在有机聚合物两相体系中，玉米蛋白α-玉米醇溶蛋白有选择性地向上相分配，将水解物限制在两相，将低相对分子质量的多肽选择性地分配到底相。本研究提出的方法可以解决传统均相反应介质中蛋白质的水解问题，如产物的选择性合成和产物与酶的分离困难。2.我们提出了一种在有机介质中具有催化活性的新型杂化酶制剂，即酶与聚合物之间形成的非共价络合物。研究发现，即使在制备阶段聚合物/酶的摩尔比仅为1，在有机介质中仍具有催化活性。当在制备阶段使用疏水缓冲液和两亲性聚合物时，该络合物表现出较高的活性。在无水异辛烷介质中，用硼酸-琥珀酸缓冲液制备的α-α-糜蛋白酶复合体的活性比天然的PEG4000-糜蛋白酶高8000倍左右。本研究提出的酶修饰方法新颖，对生物有很大的涟漪效应。该络合物在有机两相体系中也具有催化活性，可用于蛋白质的酶解。

We have aimed, in this study, (1)to control the selective production of desired peptides (e.g. angiotensin-converting enzyme (ACE)-inhibitory peptides) using the hydrolysis of corn proteins (zeins) catalyzed by proteases and (2) to develop the enzyme preparation catalytically active in organic media. The following results were obtained :1. We found that zein selectively partitioned to the upper phase, limited hydrolysates to both phases and peptides with low molecular weights selectively to the bottom phase when corn protein α-zein was hydrolyzed in organic polymer two-phase systems. The method proposed in this study can solve the problems of a protein hydrolysis in conventional homogeneous reaction media such as difficulties in the selective synthesis of products and the separation of products and an enzyme.2 We proposed the novel hybrid enzyme preparation catalytically active in organic media, i.e. the noncovalently-formed complex between an enzyme and polymers. It was found that the complex was catalytically active in organic media even when the molar ratio of the polymer/enzyme in the preparation stage was only a unity. The complex showed a high activity when hydrophobic buffers and amphiphilic polymers were used in its preparation stage. PEG4000-α-chymotrypsin complex prepared from a boric acid-succinic acid buffer solution showed ca. 8000-fold higher activity than native α-chymotrypsin in anhydrous isooctane. The method to modify enzymes proposed in this study was novel and had big ripple effects to biology. The complex was catalytically active also in organic two-phase systems and could be applied to the enzymatic hydrolysis of proteins.