[Studies on isolation, purification and antibacterial activities of beta-defensin in Yak neutrophils]

To isolate and purify beta-defensin from the neutrophils of Yak.The method of percoll gradient centrifugation was employed to purify neutrophils from Yak peripheral blood. The crude extraction from Yak neutrophils was isolated respectively through a way of extraction by 50 mL/L acetic acid, acid soluble extract of Yak neutrophils was obtained. Then it was further purified by Bio-Gel P-10 Polyacrylamide gel filtration and RP-HPLC, and 9 out of 22 apices showed antibacterial activity. 9 apices showing antibacterial activity were selected to be analyzed by mass spectrograph.The antibacterial activities of the extracts from every step were analyzed by agarose radial diffusion assay.The molecular weight of the purified Yak BNBD-1-3 was determined to be 4.2, 4.6 and 4.8 kDa by mass spectrograph. BNBD-1-3 from Yak neutrophils were able to effectively kill Escherichia coli, Staphylococcus aureus and Bacillus subtilis.Yak neutrophils have beta-defensin which have broad-spectrum antimicrobial activity, Yak defensin has an important part in innate immunity.