牛乳铁蛋白素抗菌活性及抗菌活性位点

牛乳铁蛋白素(Bovine Lactoferrcin, LfcinB)是乳铁蛋白在酸性环境下经胃蛋白酶作用N端释放的一段多肽, 它具有多种生物学功能。研究LfcinB广谱抗菌性及改变LfcinB氨基酸序列对其抗菌能力的影响, 寻找LfcinB抗菌作用的结构位点。人工合成LfcinB, 采用琼脂扩散法测定LfcinB抗菌图谱。人工合成丙氨酸取代3位半胱氨酸的LfcinB、丙氨酸取代8位色氨酸的LfcinB和去掉2个半胱氨酸的LfcinB样品, 测定最小抑菌浓度, 确定LfcinB抗菌活性位点。研究结果表明:

Antibacterial Activity and Antibacterial Action Sites of Bovine Lactoferricin

Bovine Lactoferricin is a fragment of polypeptide which derives from N-terminal of bovine lactoferrin when it is digested by pepsin in acid condition. It has many biological functions. This study was designed to research the antibiosis spectrum of LfcinB and the key functional active site of the LfcinB by amino acid substitution and peptide sequence modification. Antimicrobial spectrum of the artificial synthesized LfcinB was determined by agar-well diffusion method. The antibacterial active sites were confirmed by minimal inhibitory concentration assays. After the Cysteine at the third site and the tryptophan at the eighth site of LfcinB were substituted by alanine, or two cysteine of LfcinB were respectively, the minimal inhibitory concentration of the three artificially modified LfcinBs was assayed. Results showed that LfcinB had a broad-spectrum of antibiosis, it could restrain various bacterials, such as Gram-positive bacteria, Gram-negative bacteria, fungus and mycetes. LfcinB was stable to heat and pH, it could not be inactivated by many protease. The tryptophan at the eighth site and the intramolecular disulfide bond formed between two cysteins played a key role for antibiosis, as the functional active sites of LfcinB.