Pearson J P, Ward R, Allen A, Roberts N B, Taylor W H
Gut. 1986 Mar;27(3):243-8. doi: 10.1136/gut.27.3.243.
The ability to digest mucus, mucolytic activity of isolated pepsins and samples of human gastric juice has been assayed by measuring the fall in viscosity when incubated with purified pig gastric mucus glycoprotein. Pure human pepsin 1, the peptic ulcer associated pepsin, digested gastric mucus glycoprotein at a faster rate than did pure human pepsin 3 (the principal human pepsin), or the equivalent pig pepsin (pepsin A). At pH 2.0 pepsin 1 had twice the mucolytic activity of pepsin 3. Above pH 3.8 this difference became more marked and whereas pepsin 1 caused substantial mucolysis up to and including pH 5.1, pepsin 3 had minimal activity. At pH 4.0 pepsin 1 had six times the mucolytic activity of pepsin 3. Gastric juices from patients with duodenal ulcer each exhibited substantial mucolytic activity between pH 2 to 5, similar to that of pepsin 1. In contrast, gastric juice from non-symptomatic volunteers exhibited little mucolytic activity above pH 4. Analysis of the mucus glycoprotein by gel filtration showed that an increase in lower molecular weight, pepsin degraded, glycoprotein was associated with the fall in mucus viscosity for all enzyme preparations. These results showed that pepsin 1 can digest the mucus more effectively than pepsin 3 and at higher pH values. The raised concentrations of pepsin 1 in the juice of peptic ulcer patients may thus promote the ulcerative process by increased erosion of the mucus barrier under conditions likely to pertain in the duodenal bulb as well as the stomach.
通过测量与纯化的猪胃黏液糖蛋白孵育时的黏度下降，对分离的胃蛋白酶和人胃液样本消化黏液的能力即黏液溶解活性进行了测定。与消化性溃疡相关的纯人胃蛋白酶1消化胃黏液糖蛋白的速度比纯人胃蛋白酶3（主要的人胃蛋白酶）或等效的猪胃蛋白酶（胃蛋白酶A）更快。在pH 2.0时，胃蛋白酶1的黏液溶解活性是胃蛋白酶3的两倍。在pH 3.8以上，这种差异变得更加明显，胃蛋白酶1在pH高达5.1时都能引起显著的黏液溶解，而胃蛋白酶3的活性则极低。在pH 4.0时，胃蛋白酶1的黏液溶解活性是胃蛋白酶3的六倍。十二指肠溃疡患者的胃液在pH 2至5之间均表现出显著的黏液溶解活性，与胃蛋白酶1相似。相比之下，无症状志愿者的胃液在pH 4以上几乎没有黏液溶解活性。通过凝胶过滤对黏液糖蛋白进行分析表明，对于所有酶制剂，较低分子量的、被胃蛋白酶降解的糖蛋白增加与黏液黏度下降相关。这些结果表明，胃蛋白酶1比胃蛋白酶3能更有效地消化黏液，且在更高的pH值下也是如此。因此，消化性溃疡患者胃液中胃蛋白酶1浓度的升高可能会在十二指肠球部以及胃中可能存在的条件下，通过增加对黏液屏障的侵蚀来促进溃疡形成过程。
