胶原蛋白对胃蛋白酶消化DNA的影响

Effects of Collagen on the Digestion of DNA by Pepsin

为丰富胃蛋白酶消化核酸的理论,研究了同为胃蛋白酶底物的胶原蛋白对DNA消化的影响。在体外模拟胃液条件下,探究不同浓度的胶原蛋白、多肽和特征氨基酸对胃蛋白酶消化λDNA的影响。电泳结果表明,在生理pH3.8下反应2 h,胶原蛋白与DNA的质量比为100:1时胶原蛋白即显示出对DNA降解明显的抑制效果。胶原蛋白的消化产物——胶原蛋白肽仍能部分抑制胃蛋白酶对λDNA的消化,但是抑制程度弱于胶原蛋白。而特征氨基酸(甘氨酸、羟脯氨酸和谷氨酸)对λDNA的消化无明显影响。研究表明,胶原蛋白可抑制胃蛋白酶对DNA的消化,抑制作用与蛋白分子聚合度相关。抑制产生的原因可能是胶原蛋白阻碍DNA与胃蛋白酶的结合,从而对DNA消化产生抑制作用。

To enrich the theory of digestion of nucleic acids by pepsin,we focused on collagen which is also a substrate of pepsin,and the effect of collagen on the digestion of DNA by pepsin was studied.The effects of different concentrations of collagen,peptides,and characteristic amino acids on digestion of λDNA by pepsin were investigated by using simulated gastric juice in vitro.The electrophoresis showed that when the mass ratio of collagen to DNA was 100:1,collagen inhibited the degradation of DNA for 2 h at physiological pH 3.8.The collagen digestion product,collagen peptide,still partially inhibited the digestion of λDNA by pepsin,but its inhibition was weaker than collagen.The characteristic amino acids (glycine,hydroxyproline,and glutamic acid) have no significant effect on the digestion of λDNA.Studies have shown that collagen can inhibit the digestion of DNA by pepsin,and the inhibitory effect is related to the degree of polymerization of protein molecules.The reason for the inhibition may be that collagen prevents the binding of DNA and pepsin,thus prohibiting DNA from digestion.