壳聚糖及其组成的寡糖、单糖对胃蛋白酶消化DNA的影响

Effects of chitosan and its constituents oligosaccharides and monosaccharides on digestion of DNA by pepsin

为丰富胃蛋白酶消化DNA的理论,进一步了解胃蛋白酶消化DNA的机制,研究了水产品基质中特征壳聚糖及组成其的寡糖(壳寡糖)、单糖(氨基葡萄糖、N-乙酰葡糖胺)对胃蛋白酶消化DNA的影响,并在体外模拟胃液条件下,探究了不同比例的糖与DNA对胃蛋白酶消化鲑鱼精DNA、λDNA的影响。结果表明:在生理pH下反应2 h,壳聚糖与DNA的质量比为0.5∶1时,壳聚糖即显示出对降解DNA明显的抑制效果;当壳寡糖与DNA的质量比为5∶1时,抑制效果较为明显;而氨基葡萄糖、N-乙酰葡糖胺与DNA的质量比为1∶1~240∶1时对消化均无抑制作用。研究表明,壳聚糖、壳寡糖可抑制胃蛋白酶对DNA的消化,其原因可能是带正电的糖可与带负电的DNA相互作用,或糖与胃蛋白酶发生了结合,从而对DNA消化产生保护作用。

The effect of chitosan and its constituents oligosaccharides(chitosan oligosaccharides)and monosaccharides(glucosamine and N-acetylglucosamine)in the matrix of aquatic products on digestion of DNA by pepsin was investigated to understand theory of pepsin digestion of DNA and to further explore its mechanism.The effects of different mass ratios of sugar to DNA on pepsin digestion of salmon sperm DNA andλDNA were evaluated in vitro by using simulated gastric juice.The electrophoresis showed that chitosan inhibited the degradation of DNA at mass ratio of chitosan to nucleic acid=0.5∶1 for 2 hours at physiological pH,the obvious inhibition at mass ratio of oligochitosan to nucleic acid=5∶1.However,there was no inhibitory effect of glucosamine and N-acetylglucamine on digestion within the range of 1∶1-240∶1 mass ratio of DNA to glucosamine.It is concluded that chitosan and oligochitosan can inhibit the digestion of DNA by pepsin due to the interaction of positively charged sugars with negatively charged DNA,or due to the binding of sugars with pepsin as to protect DNA from digestion.