胃蛋白酶Pepsin A性质与结构分析

Property and Structure Analysis of Pepsin A

胃蛋白酶是一种肽链内切酶,它将蛋白质分解成较小的肽(即蛋白酶)。在胃中产生,是人类和许多其他动物消化系统中的主要消化酶之一,在那里它有助于消化食物中的蛋白质。由胃壁中的主要细胞释放的胃蛋白酶原,与胃液的盐酸混合后,胃蛋白酶原激活成为胃蛋白酶。本文对胃蛋白酶的基本特性进行了初步分析,通过分析胃蛋白酶氨基酸组成、疏水性表明胃蛋白酶具有酸性蛋白、胶原蛋白、黏蛋白等特征,整体呈现疏水性。利用MEGA软件进行胃蛋白酶系统发育分析,结果表明人与日本猕猴亲缘关系高度相近,而牛和日本猕猴两者的亲缘关系较远。使用PSORTII分析工具对胃蛋白酶亚细胞定位进行预测,结果表明胃蛋白酶主要分布于细胞外。最后,采用同源建模法构建了胃蛋白酶的三级结构,并对建模质量进行了评估,结果表明三级结构预测总体准确。

Pepsin is an endopeptidase that breaks down proteins into smaller peptides(i.e.,proteases).It is produced in the stomach and is one of the main digestive enzymes in the digestive system of human beings and many other animals,where it helps to digest protein in food.Pepsinogen that released by major cells in the stomach wall is activated to become pepsin after being mixed with hydrochloric acid in gastric juice.This paper makes a preliminary analysis of the basic characteristics of pepsin.By analyzing the amino acid composition and hydrophobicity of pepsin,it shows that pepsin has the characteristics of acidic protein,collagen and mucin,which shows hydrophobicity as a whole.Using MEGA software to make a phylogenetic analysis on pepsin,the results showed that the genetic relationship between human and Japanese macaques is very close,while the genetic relationship between cattle and Japanese macaques was far away.Using PSORTII analysis tool to make a prediction on the subcellular localization of pepsin,the results showed that pepsin was mainly distributed outside cells.Finally,the homologous modeling method was used to construct the three-level structure of pepsin,and the modeling quality was evaluated.The results showed that the three-level structure prediction was accurate overall.