Primate pepsins : evolution, function, and adaptation to feeding strategy

胃蛋白酶是脊椎动物（包括人类）的胃消化蛋白酶，有五种形式，即，胃蛋白酶A、B和F，胃蛋白酶和凝乳酶，它们是从一种共同的祖先天冬氨酸蛋白酶进化而来的。该特异性可以用由Tyr^<189>、Ile^、Ile <213>^<300>、Met^<289>、瓦尔/Leu^<291>和Leu^组成的S1'亚位点的非常疏水的性质来很好地解释<298>。前三个残基在胃蛋白酶家族酶中非常保守。从红毛猩猩（Pongo pygmaeus）胃粘膜中克隆了14个不同的胃蛋白酶原-A cDNA和1个胃蛋白酶原-C cDNA。由于胃内酶水平的增加和酶特异性的多样化，猩猩的极端繁殖可能有利于对草本食物的消化。

Pepsins are gastric digestive proteinases in vertebrates, including man. There are five forms, i.e., pepsins A, B, and F, gastricsin, and chymosin, which have evolved from a common ancestral aspartic proteinase. The specificity is well explained with the very hydrophobic nature of the S1' subsite, consisting of Tyr^<189>, Ile^<213>, Ile^<300>, Met^<289>, Val/Leu^<291>, and Leu^<298>. The first three residues are well conserved in pepsin family enzymes. Fourteen different pepsinogen-A cDNAs and one pepsinogen-C cDNA have been cloned from gastric mucosa of the orangutan, Pongo pygmaeus. The extreme multiplication in the orangutan might be advantageous for the digestion of herbaceous foods due to the increase in the level of enzymes in stomach and the diversification of enzyme specificity.