摘要
目的 观察阳离子多肽 Mastoparan- 1(MP- 1)的体内、外抗菌作用。方法 采用微量稀释法观察MP- 1对 18株细菌的最低抑菌浓度 (MIC)和最低杀菌浓度 (MBC) ;将 MP- 1(10 0 μg/ml)与大肠埃希氏菌ATCC2 5 92 2 37℃共孵育 5、10、15 min,透射电镜下观察细菌形态的变化 ;应用生物传感器检测 MP- 1与内毒素 (L PS)及其活性中心类脂 A(L ipid A)结合的亲和力 ;以 ATCC2 5 92 2活菌攻击小鼠 (2× 10 9CFU/2 0 g体重 ) ,观察 MP- 1(3mg/kg)对小鼠的保护作用。结果 MP- 1具有一定的体外抗菌活性 ;MP- 1与细菌作用 5 min时 ,细菌外膜粗糙 ,内膜轮廓模糊 ,10 min时胞质不均匀 ,可见空泡 ,15 min时菌体肿胀 ,胞内空泡变性明显加重 ;MP- 1对 L PS/L ipid A均具有较高的亲和力 ;MP- 1可显著提高活菌攻击小鼠的 3天存活率。结论 MP- 1对革兰氏阴性菌及革兰氏阳性菌均具有一定的抗菌作用 ,它对大肠埃希氏菌 ATCC2 5 92 2的杀菌活性可能与其对细菌细胞膜破坏、通透性增加有关 ,此特性可能基于 MP- 1与细菌外膜 L PS/L ipid A的结合作用实现。
Objective To observe the antibacterial activity of MP-1 in vitro and in vivo. Methods The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of MP-1 for 18 tested strains were measured by microdilution method. The morphologic changes of E.coli ATCC25922 were observed after incubated with MP-1 (100μg/ml) for 5, 10 and 15min respectively by transmission electron microscope (TEM). The affinity of MP-1 for LPS and Lipid A was assayed by biosensor. (下转第475页) In vivo, a lethal dose (2×109CFU/20g body weigh) of viable E.coli ATCC259222 was injected into mice by tail vein, and the activity of MP-1 (3mg/kg) protecting mice from bacterial challenge were observed. Result Results revealed that the MP-1 antibacterial activity was moderately against Gram-positive and Gram-negative bacteria compared with other tested antibiotics. Asymmetry and vacuoles in the cytoplasm of bacteria were shown after E.coli ATCC25922 was incubated with MP-1 for 5min, cell swelling for 10min and severe degeneration for 15min. MP-1 binded with high-affinity to LPS and Lipid A with dissociation constant (Kd) of 484 nmol and 456 nmol, respectively. Moreover, MP-1 could improve the 3-day survival rate of mice from bacterial challenge. Conclusion MP-1 demonstrated antibacterial activity against Gram-positive and Gram-negative bacteria, and its bactericidal action for E.coli ATCC25922 might be caused by the increase in membrane permeability coming from the destruction of membrane structure, which might be based on its affinity for LPS and Lipid A.
出处
《中国抗生素杂志》
CAS
CSCD
北大核心
2004年第8期454-458,475,共6页
Chinese Journal of Antibiotics
基金
国家重点基础研究发展规划资助项目 (G1 9990 542 0 3)。
关键词
阳离子多肽
抗菌活性
内毒素
Cationic peptide
Antibacterial activity
Lipopolysaccharide
