جستجوی مقالات مرتبط با کلیدواژه « Catalytic Domain » در نشریات گروه « پزشکی »

Botulism, a syndrome caused by food poisoning, results from use of food contaminated with the botulinum toxin, which is very dangerous and deadly. Botulism is caused by the effects of bacterial toxins on the terminals of the motor nerves. Botulinum neurotoxins are among the most potent toxins. The aim of this study was to investigate expression, purification and, evaluation of the immunogenicity of the recombinant BoNT/B-HcC protein as an immunogen candidate in mice.

The C-terminus of the receptor-binding domain of  botulinum neurotoxin type B(BoNT/B-HcC) was selected as the antigen for bioinformatics evaluations. The pET17b-BoNT/B-HcC plasmid was transferred to E. coli BL21(DE3) by heat shock. The recombinant protein was purified and analyzed by SDS-PAGE. After verification of the recombinant protein by western blot, immunization of mice was performed. Antibody titers of recombinant proteins were evaluated by indirect ELISA and the results were compared using t-test.

The codon adaptation index (CAI) of the optimized gene was 0.99. The percentage of codons having high-frequency distribution was improved to 78%. Restriction analysis confirmed the 1119 bp construct gene and the recombinant protein with a molecular weight of 43.8 kDa was expressed in the prokaryotic host. The total yield of purified protein was 23 mg of protein per liter of culture. Immunization of mice induced serum antibody response. Statistical analysis showed that the antibody titer was significantly different compared to that of the control sample.

The designed recombinant antigen showed high antigenicity that could be considered as an immunogen against botulinum type B neurotoxin in future studies.

Aims: Botulinum neurotoxins are the strongest known bacterial toxins that cause muscle paralysis due to inhibition of acetylcholine release. Design of inhibitors is still pursued as a major strategy for intracellular inhibition of poisoning caused by these toxins. Investigation of the potential function of design inhibitors, pure poison or catalytic area is essential. The aims of present study were expression and purification of recombinant catalytic domain of botulinum neurotoxin type E (BoNT/E) Type E from a synthetic gene.
In this experimental study, the sequence of the botulinum neurotoxin type E light chain was adopted from GeneBank and codons were optimized according to E.coli BL21 (DE3) codon usage. Other bioinformatics tools were exploited to reach the optimum expression of the gene in the mentioned host. The resultant (gene) was then ordered to synthesize and cloning in pET28a () expression vector. The recombinant vector was transferred into E. coli BL21 (DE3) host cells. The expression of the protein was induced by addition of IPTG. The expression conditions were changed to obtain a soluble expression of the protein. Then, the protein was purified by an affinity chromatography, followed by a further purification with amicon filter. SDS-PAGE was used to evaluate expression and purification of the protein and Western blotting was performed to confirm the expressed protein.
Finding: Codon Adaptation Index of the gene increased to 0.85. The third predicted structure showed good quality. The thermodynamic analysis of the mRNA structure showed that the predicted structure is stable. The soluble expression was obtained in 18°C and 18h induction by 1 mM IPTG. Protein production with higher more than 90% purity was confirmed.
Optimization of the protein expression conditions resulted in producing the solution in the culture medium by E. coli BL21 as host.

Botulinum neurotoxin type A, structurally consists of a 50KD light chain and a 100 KD heavy chain linked by a disulfide bond. The protein can further be divided into three functional domains of which catalytic domain corresponds to the light chain. In this research we aimed to produce recombinant catalytic domain in order to obtain a protective protein. Bacteria were grown in anaerobic conditions and genomic DNA was extracted by alkaline method. Following the gene coding a set of primers was designed and the catalytic domain was amplified through PCR. The PCR product was then cloned into three expression vectors namely pRSETA, pET28a and pET32a. The expressed protein was analyzed on SDS-PAGE and confirmed by ELISA and western blotting and then purified by affinity chromatography. In this research the maximum expression was obtained at 0.5 mM IPTG,OD600:0.6 and 15 hours of induction at 30˚C. The protein so expressed was purified by affinity coulmn chromatography. The antibody raised against recombinant protein could protect the rats by 100 LD50. Though the expression of AT- rich genes in E.coli system is low, we could obtain an appropriate level of expression in this study. The purification of recombinant protein in the early stages was elusive in the extreme by affinity chromatography due to the weak binding of histidine N-terminal to the column, howerer 90% purification was achieved through modification of the technique. The antibody produced against this domain was less protective compared to that of binding domain.