非天然氨基酸取代对非洲爪蟾皮肤肽PGLa-H血清稳定性及生物活性的影响

Effects of unnatural amino acid substitution on the serum stability and biological activityof peptide derived from the skin of Xenopus laevis

目的 改造非洲爪蟾分泌的抗菌肽PGLa-H的结构,增强其血清稳定性与生物活性。方法 以天然抗菌肽PGLa-H为模板,将该多肽序列中的L-丙氨酸以非天然的氨基异丁酸(Aib)进行部分取代。利用固相多肽合成技术合成多肽;评价多肽在血清中的稳定性;测定多肽对4种不同细菌菌株的抗菌活性,通过肉汤稀释法判断最小抑菌浓度;评价不同盐离子存在对多肽抗菌活性的影响;评价多肽的溶血活性与细胞毒性。结果 通过Aib取代,得到PGLa-H(Aib),减少了血清中蛋白酶对多肽的降解,并提高了多肽对4种不同细菌的抗菌活性,无明显的溶血活性与细胞毒性。结论 Aib取代能增强多肽的血清稳定性和生物活性,且具有良好的生物相容性。

OBJECTIVE To modify the antimicrobial peptide PGLa-H secreted by Xenopus laevis,to enhance its serum stability and biological activity.METHODS Using the natural antimicrobial peptide PGLa-H as a template,L-alanine in the peptide sequence was partially replaced by unnatural aminoisobutyric acid(Aib).The peptides were obtained by solid-phase peptide synthesis.The stability of peptides in serum was evaluated.The antimicrobial activity of peptides against four different bacterial strains was determined,and the minimum inhibitory concentration(MIC)was determined by broth dilution method.The effect of different salt ions on the antimicrobial activity of peptides was evaluated.The hemolytic activity and cytotoxicity of peptides were evaluated.RESULTS Substitution of L-alanine with Aib in PGLa-H(Aib)could reduce the degradation of peptides by serum proteases,and improve the antimicrobial activity of peptide against four different bacterial strains,without obvious hemolytic activity or cytotoxicity.CONCLUSION Aib substitution can enhance the serum stability and biological activity of peptides,showing good biocompatibility.