Optimization of induction parameters, structure quality assessment by ATR-FTIR and in silico characterization of expressed recombinant polcalcin in three different strains of Escherichia coli.

The inhalation of Chenopodium album (C. album) pollen, especially polcalcin (Che a 3), has been reported as a significant source of allergic respiratory symptoms. This study was conducted to characterize biophysical differences of recombinant polcalcin come from three different Escherichia coli strains using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), optimize recombinant polcalcin expression, and linear B-cell epitopes identification using in silico methods. ATR-FTIR results of purified proteins showed spectra intensity variance in the amide I region, while there were no changes in pick position and shape of the bands. SHuffle® T7 Express was selected for subsequent optimization due to ability in the correction of the mis-oxidized bonds and promotes proper folding which was validated by ATR-FTIR analysis results. Then, Response Surface Methodology was performed to optimize critical factors including induction temperature, duration of induction, and concentration of inducer. The best partitioning conditions were achieved in 1.5 mM IPTG for 10.97 h at 29.9 °C. Finally, prediction of polcalcin B-cell epitopes was carried out which indicated the presence of 4 different epitopes. Together, the results may help to the development of diagnostic approaches and also vaccine manufacture for desensitization and modulation of the allergic response in patients.

Development of high-throughput quantum dot biosensor against Polymyxa species.

The plasmodiophoromycete Polymyxa betae and P. graminis are eukaryotic biotrophic parasites residing in the roots of chenopodiacae and gramineae plants. They are natural transmitting agents of several important plant viruses such as are beet necrotic yellow vein virus (BNYW), beet soil borne mosaic virus (BSBMV), wheat soil-borne mosaic virus (WSBMV). Developing advanced high-throughput diagnostic methods capable of accurate detection of these pathogens could assist with the screening programs and consequently with the development of disease-resistant germplasms. In the present study, a previously developed quantum dots (QDs) FRET-based nano-biosensor was upgraded to a high-throughput version. QDs were functionalized with a specific antibody against the P. betae's specific glutathione-S-transferase (GST) protein. On the other hand, GST was conjugated to Rhodamine dye. Ninety six-well polystyrene plates were used as the detection platform. The mutual affinity of the antigen and the antibody brought the CdTe QDs and rhodamine together close enough to allow the resonance dipole-dipole coupling required for fluorescence resonance energy transfer (FRET) to occur. The immunosensor constructed showed a high sensitivity and specificity of 100%, and was successfully used for high-throughput screening of 96 real samples with consistent results within the course of less than 30 minutes.