Optimization of S-layer protein purification from Deinococcus radiodurans strain R1

S-layer proteins of Deinococcus radiodurans are the best self-assemble systems among other proteins that have an essential role in the fabrication of nanowires. Therefore, the purification of these proteins is necessary. The purpose of this research was to optimize the purification of s-layer protein from D. radiodurans with the response surface method. The three factors of SDS concentration, incubation time and mass percent in five levels were considered, and 20 runs were designed by Design-Expert software with a central composite method. Each run includes microbe culture, mass cell preparation, microbe incubation in specific SDS concentration and time and mass percent, separation of the bacteria from detergent with a centrifuge at 5000g, sedimentation of s-layer proteins from detergent solution with a centrifuge at 20000g, determination of protein concentration, and protein purity by Bradford and SDS-PAGE methods, respectively. Finally, the data obtained were analyzed.  Analysis of the results demonstrated that at the 95% confidence level, the effect of the detergent concentration factor on the purified protein percent was more than other factors. The optimization results of factors are 5.64% SDS concentration, 7.33% mass percent, and 3 hours incubation time. At optimized conditions the protein concentration and purity percent were obtained 0.584 mg/ml and 47.61% respectively.