Kageyama T, Takahashi K
J Biochem. 1980 Aug;88(2):571-82. doi: 10.1093/oxfordjournals.jbchem.a133005.
Upon activation of human pepsinogen A at pH 2.0 in the presence of pepstatin, an intermediate form was generated together with pepsin A. This activation intermediate could be separated from pepsinogen A and pepsin A by DE-32 cellulose chromatography at pH 5.5. It had a molecular weight intermediate between those of pepsinogen A and pepsin A, and contained about half the number of basic amino acid residues in pepsinogen A. It had phenylalanine as the amino(N)-terminal amino acid, and was deduced to be generated by release of N-terminal 25 residue segment from pepsinogen A. Amino acid sequence determination of the N-terminal portions of pepsinogen A and the intermediate from enabled us to elucidate the entire acid sequence of the 47-residue activation peptide segment as follow: [Formula: see text]. On the other hand, upon activation of pepsinogen A at pH 2.0 in the absence of pepstatin, cleavage of the activation segment occurred at several additional bonds. In addition, upon activation both in the presence and in the absence of pepsitatin, an additional activation intermediate, designated pepsin A', was formed in minor quantities. This form was identical with pepsin A, except that it had an additional Pro-Thr-Leu sequence preceding the N-terminal valine of pepsin A.
在胃蛋白酶抑制剂存在的情况下，于pH 2.0激活人胃蛋白酶原A时，会产生一种中间形式以及胃蛋白酶A。这种激活中间体可在pH 5.5时通过DE - 32纤维素色谱法与胃蛋白酶原A和胃蛋白酶A分离。它的分子量介于胃蛋白酶原A和胃蛋白酶A之间，碱性氨基酸残基数量约为胃蛋白酶原A的一半。它以苯丙氨酸作为氨基（N）末端氨基酸，据推测是由胃蛋白酶原A释放N末端25个残基片段而产生的。对胃蛋白酶原A和该中间体N末端部分的氨基酸序列测定，使我们能够阐明47个残基激活肽段的完整氨基酸序列如下：[公式：见文本]。另一方面，在无胃蛋白酶抑制剂的情况下于pH 2.0激活胃蛋白酶原A时，激活片段在几个额外的位点发生切割。此外，无论有无胃蛋白酶抑制剂存在，激活过程中都会少量形成另一种激活中间体，称为胃蛋白酶A'。这种形式与胃蛋白酶A相同，只是在胃蛋白酶A的N末端缬氨酸之前有一个额外的Pro - Thr - Leu序列。
