XPA, also known as DNA repair protein complementing XP-A cells, belong to the XPA family. This protein is involved in DNA excision repair. It Initiates repair by binding to damaged sites with various affinities, depending on the photoproduct and the transcriptional state of the region. Defects in XPA are a cause of xeroderma pigmentosum complementation group A (XP-A), which is a rare human autosomal recessive disease characterized by solar sensitivity, high predisposition for developing cancers on areas exposed to sunlight and, in some cases, neurological abnormalities. Recombinant human XPA protein, fused to His-tag at N-terminus, was expressed in E.coli.