Ichishima E, Ojima M, Yamagata Y, Hanzawa S, Nakamura T
Department of Applied Biological Chemistry, Faculty of Agriculture, Tohoku University, Sendai, Japan.
Phytochemistry. 1995 Jan;38(1):27-30. doi: 10.1016/0031-9422(94)00552-5.
An aspartic proteinase, rhizopuspepsin (EC 3.4.23.21), from Rhizopus hangchow was purified. The M(r) and isoelectric point were determined as ca 37,000 and 4.5, respectively. The first 19 amino acids in the N-terminal region were SGSGVVPMTDYEYDIEYYG. The contents of the alpha-helix, beta-structure and random coil were calculated to be ca 7.5, 88.9 and 2.7%, respectively. The enzyme can activate trypsinogen at pH 3.0. The activity was completely inactivated by pepstatin A. The specificity and mode of action of the enzyme were investigated with oxidized insulin B-chain at pH 3. The enzyme hydrolysed primarily two peptide bonds, the Leu15-Tyr16 bond and the Tyr16-Leu17 bond, while additional cleavage of the bonds, Ala14-Leu15 and Phe24-Phe25 was also noted.
从杭州根霉中纯化出一种天冬氨酸蛋白酶——根霉胃蛋白酶（EC 3.4.23.21）。其相对分子质量和等电点分别测定为约37,000和4.5。N端区域的前19个氨基酸为SGSGVVPMTDYEYDIEYYG。计算得出α-螺旋、β-结构和无规卷曲的含量分别约为7.5%、88.9%和2.7%。该酶在pH 3.0时可激活胰蛋白酶原。其活性被胃蛋白酶抑制剂A完全抑制。在pH 3条件下，用氧化胰岛素B链研究了该酶的特异性和作用方式。该酶主要水解两个肽键，即Leu15-Tyr16键和Tyr16-Leu17键，同时也观察到Ala14-Leu15和Phe24-Phe25键的额外裂解。
