条斑紫菜蛋白酶解多肽的抑菌活性

The Antibacterial Activity of Peptides From Porphyra yezoensis

中文关键词: 条斑紫菜  水溶性蛋白质  胃蛋白酶  多肽  金黄色葡萄球菌  抑菌活性

英文关键词: Porphyra yezoensis  Antibacterial peptide  Staphylococcus aureus  Antibacterial activity

中文摘要:

      以条斑紫菜为原料，分别提取水溶、酸溶、碱溶、盐溶性蛋白质，并用6种蛋白酶酶解，将所得24种酶解物采用琼脂孔穴扩散法对金黄色葡萄球菌(Staphylococcus aureus)、四联微球菌(Micrococcus tetragenus)、枯草杆菌(Bacillus subtilis)以及大肠杆菌(Escherichia coli) 4种菌进行抑菌活性测定。结果显示，水溶性胃蛋白酶酶解物的抑菌活性最优。将水溶性蛋白质经硫酸铵沉淀以及超滤分级，比较不同饱和度硫酸铵沉淀所得蛋白质酶解物以及不同分子量多肽的抑菌效果。结果显示，水溶性蛋白在硫酸铵饱和度为40%、50%时沉淀所得蛋白的胃蛋白酶酶解物中，相对分子质量小于5 kDa的级分抑菌效果最为明显。此外，对该级分进行了抑菌活性影响因素的初步研究，结果表明该级分热稳定性以及酸碱稳定性均较好，有望开发为天然的食品防腐剂。

英文摘要:

      Enriched in proteins and with similar amino acid compositions to the terrestrial vegetables, Porphyra has become an important economic marine algae with high nutritional and medical values in China. In order to obtain peptides holding antibacterial activity, Porphyra yezoensis was utilized as raw material and water, NaCl, HCl and NaOH were used as the solvents. Water-dissolved, salt-dissolved, acid-dissolved and alkaline-dissolved proteins were prepared by the extraction, ammonium sulfate salting-out, dialysis and freeze-drying, respectively. The four types of proteins were hydrolyzed respectively by pepsin, papain, neutral protease, trypsin, acid protease and compound protease under the optimum conditions for each enzyme. Twenty-four hydrolysates were selected to evaluate the antibacterial activity to Staphylococcus aureus, Micrococcus tetragenus, Bacillus subtilis and Escherichia coli that were used as the indicator bacteria. Moreover, the proteins were divided into 7 portions by fractional precipitation with different saturation degree of ammonium sulfate; and their hydrolysates were fractioned to peptide fragments with different molecular weights by ultrafiltration. The best antibacterial peptides were evaluated by comparing the inhibitory effects of hydrolysates to the indicator bacteria. The result showed that the zymolyte of water-soluble proteins hydrolyzed by pepsin presented the strongest antibacterial activity. Thus, antimicrobial peptides were achieved via fraction precipitation by ammonium sulfate for the proteins, ultrafiltration for their zymolyte, and the ammonium sulfate saturation at 40%−50%, and the range of molecular-weight was less than 5 kDa. In addition, factors (such as temperature, medium pH and antimicrobial peptides concentration) that affect the antibacterial activities were also studied. The results indicated that the antimicrobial peptides from Porphyra yezoensis possessed good thermal and acid-base stability, which may be candidate for a safe food preservative.