Preparation, Isolation And Purification Of Lactoferricin Bovine And Study On Its Antibacterial Properties

Lactoferricin bovine is produced by pepsin digestion of N-terminal region of bovine Lactoferrin in acidic condition. It is a peptides section composed of 25 amino acid and has the functions of antibacterial, anti-virus, restraining the growth of tumour cells, adjusting the express of gene and immunity.As an antibacterial peptide, lactoferricin B can be applied in foods, health foods, medicine, and so on, with the wide prospects of application and exploiture. In this paper, high purity lactoferricin B was produced by iron exchange chromatography with the technics of centrifugation, ultrafiltration and freeze-drying. Based on mensurating the minimum inhibitory concentration of lactoferricin B, the paper studied the effects of several food additives on its antibacterial activities. In addition, the paper gave an elementary study on the antiphlogistic ability of bovine Lactoferrin. The experiment results indicated that the optimum enzyme hydrolysis conditions of producing lactoferricin B by pepsin digestion of bovine Lactoferrin were substrate 5%(w/v), enzyme: substrate ratio [E/S] 1:30(w/w) and time 60 minutes. It was found that the purity of lactoferricin B of 95% could be produced with the operations: first, ultrafiltrating the crude isolation solution with ultrafiltration membrane of MWCO10000Da and 6000Da; second, adsorbing the lactoferricin B with cation-exchange medium Butyl-Toyopearl 650M; and then rinsing the medium with pH5.0 buffer of citric aicid- phosphoric acid; the last, desorbing the lactoferricin B with 10mM HCl (lactoferricin B of purity 40.6% and 80.5% could also be produced ) .The minimum inhibitory concentration of lactoferricin B against E.coli was 15μg/mL. The effects of four kinds of composite sweeteners, four kinds of crude sweeteners and four antiseptic on the antibacterial activities of lactoferricin B also be mensurated.