Talarico T L, Dev I K, Bassford P J, Ray P H
Wellcome Research Laboratories, Department of Molecular Genetics and Microbiology, Research Triangle Park, NC 27709.
Biochem Biophys Res Commun. 1991 Dec 16;181(2):650-6. doi: 10.1016/0006-291x(91)91240-d.
Highly purified preparations of signal peptidase I (36 kDa) were found to undergo an apparent inter-autocatalytic degradation at 4 degrees C and 37 degrees C. The disappearance of the 36 kDa protein coincided with the stable appearance of a 31 kDa and a 5 kDa species. Amino-terminal sequencing of the 31 kDa product indicated a site specific cleavage following Ala38-Gln-Ala of signal peptidase I. The 31 kDa fragment was purified and shown to have 100-fold less activity than the native enzyme, with pre-maltose binding protein as a substrate.
人们发现，高度纯化的信号肽酶I（36千道尔顿）制剂在4摄氏度和37摄氏度下会发生明显的自身催化降解。36千道尔顿蛋白质的消失与31千道尔顿和5千道尔顿物质的稳定出现同时发生。对31千道尔顿产物进行的氨基末端测序表明，信号肽酶I在丙氨酸38 - 谷氨酰胺 - 丙氨酸之后发生了位点特异性切割。31千道尔顿的片段被纯化出来，结果显示，以麦芽糖结合蛋白前体作为底物时，其活性比天然酶低100倍。
