Macpherson E, Tomkinson B, Bålöw R M, Höglund S, Zetterqvist O
Department of Biochemistry, University of Uppsala, Sweden.
Biochem J. 1987 Nov 15;248(1):259-63. doi: 10.1042/bj2480259.
Tripeptidyl peptidase II is an extralysosomal serine peptidase of an unusually large size, i.e. Mr greater than 10(6) for the native enzyme and Mr 135000 for the subunit. The enzyme from human erythrocytes was studied by electron microscopy on samples negatively stained by ammonium molybdate. Two different structural representations of the purified enzyme were obtained, both with a length of about 50 nm, and consisting of repetitive substructures. Upon dialysis of the enzyme against a Tris/HCl buffer, the activity was gradually decreased. This decrease was shown to parallel the dissociation of the large enzyme structures into smaller ones, the smallest measuring 3 nm by 10 nm and apparently corresponding to the repetitive substructures. The results indicate that a large polymeric form of the enzyme is a prerequisite for full activity.
三肽基肽酶II是一种胞外溶酶体丝氨酸肽酶，其分子尺寸异常大，即天然酶的分子量大于10^6，亚基的分子量为135000。用人红细胞中的该酶对经钼酸铵负染色的样品进行电子显微镜研究。获得了纯化酶的两种不同结构表征，二者长度均约为50nm，且均由重复亚结构组成。将该酶在Tris/HCl缓冲液中透析后，其活性逐渐降低。结果表明，这种活性降低与大的酶结构解离成较小结构相平行，最小的结构尺寸为3nm×10nm，显然对应于重复亚结构。结果表明，酶的大聚合物形式是其具有完全活性的前提条件。
