Cloning and expression of a gene encoding shortened LfcinB(1-15)-Melittin(5-12) hybrid peptide in Escherichia coli BL21(DE3) / 生物工程学报

In order to get new antibacterial peptide, we designed a hybrid peptide LfcinB(1-15)-Melittin(5-12), composed of 1-15 amino acid residues of bovine Lactoferricin and 5-12 amino acid residues of Melittin. According to the bias of codon utilization of Escherichia coli, We synthesized the gene encoding the hybrid peptide. We inserted the gene between the sites of Nco I and Sal I of pET-32a and obtained the recombinant expression vector for heterologous expression of LfcinB(1-15)-Melittin(5-12) in Escherichia coli. We used Escherichia coli BL21(DE3) as expression host for the recombinant plasmid. After induced by isopropyl-beta-D-thiogalactoside (IPTG) under the optimized conditions, we realized the fusion protein was successfully expressed. The fusion protein was expressed in soluble form and the level was more than 35% of the total proteins. With (His)6 x Tag, the fusion protein was easily purified by His x Bind Purification Kit. After purification, we obtained 35 mg of fusion protein from 1 L of culture medium. At last, we accomplished that the peptide LfcinB(1-15)-Melittin(5-12) was released from the fusion protein cleaved by enterokinase. The recombinant LfcinB(1-15)-Melittin(5-12) showed antimicrobial activity assayed by agar diffusion test. This is the first report on the heterologous expression of the hybrid antibacterial peptide LfcinB(1-15)-Melittin(5-12) in Escherichia coli and also provides basis for next cost-effective expression of other antimicrobial peptides in genetic engineering.

Expression of neuroglobin in cerebral cortex of traumatic brain injury rats / 解放军医学杂志

Objective To observe the expression of neuroglobin (Ngb) in cerebral cortex of traumatic brain injury rats, and investigate the role of neuroglobin in brain injuries. Methods A traumatic brain injury rat model was constructed with Feeney's method. Fifiteen experiment animals were divided randomly into normal control group, 12h-post-trauma group and 36h-post-trauma group (5 each). Immunohistochemistry and image analysis techniques were used to measure the area, optic density (OD) value and integrated optic density (IOD) value of Ngb immunoreactive products in primary somatosensory cortex (S1) and retrosplenial granular b cortex (RSGb), which was located in the inner side and out side of traumatic brain injury cavity in coronal section of rat brain respectively. Results Ngb immunoreactive products were significantly increased after brain trauma, especially in 36h-post-trauma group. The image analysis showed that there was no significant difference of immunoreactive product area in the 3 groups (P