SRM is an enzyme that catalyzes the transfer of the propylamine group from S-adenosylmethioninamine to putrescine in the biosynthesis of spermidine. The polyamines putrescine, spermine, and spermidine are ubiquitous polycationic mediators of cell growth and differentiation. This protein is one of four enzymes in the polyamine-biosynthetic pathway and carries out the final step of spermidine biosynthesis. Recombinant human SRM protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.