Antibacterial Activity and Antibacterial Action Sites of Bovine Lactoferricin / 微生物学通报

ABSTRACT

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.