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

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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.