Low Concentration of Salt triggers Elastin-like Polypeptides Inverse Transition to Purify 1,3-propanediol Oxidoreductase

Elastin-like polypeptides have been widely used as the purification tag.Non-chromatographic purification of ELPs fusion proteins,termed inverse transition cycling(ITC),exploits the reversible soluble-insoluble phase transition behavior imparted by the ELPs tag.This study found that the novel ELPs tag could purify 1,3-propanediol oxidoreductase(PDOR) efficiently.The ELPs aggregated with 0.8 mol/L Na2CO3 at room temperature,and then PDOR,which was linked with the ELPs,was purified by ITC.The purity could reach about 98%,and the purification fold was above 8,about 7 times that of Histag purification method.By comparing the properties of the purified fusion ELPs-PDOR and His-PDOR,we found that ELPs tag hardly affects the target protein,suggesting that it can be used during the biocatalysis process.The method with low salt concentration to induce the phase transition of ELPs can avoid potential adverse effect on enzyme structure and property,thus being advantageous in protein purification.