Enhancement of the solubility and stability of d-amino acid oxidase by fusion to an elastin like polypeptide

An elastin-like polypeptide (ELP) was fused to d-amino acid oxidases (DAAO). ELP-DAAO exhibited a better solubility in aqueous solutions than DAAO, and its enzymatic activity is about 1.6 times that of DAAO. The stability of the proteins was investigated by interacting with urea at various concentrations. The circular dichroism and fluorescence spectra were measured. The results demonstrated that that ELP-DAAO exhibited a much better stability than DAAO, and ELP-DAAO has retained the α-helix content with a high percentage even at a high urea concentration. The results of this work have demonstrated that the ELP tag can be utilized to purify DAAO, in the meantime the solubility and stability of the enzyme are improved.