PYCR2 also known as pyrroline-5-carboxylate reductase 2 isoform 1, belongs to the pyrroline-5-carboxylate reductase family. This protein catalyzes the conversion of pyrroline-5-carboxylate to proline, which is the last step in proline biosynthesis. The 3 substrates of this enzyme are L-proline, NAD+, and NADP+, whereas its 4 products are 1-pyrroline-5-carboxylate, NADH, NADPH, and H+. Recombinant human PYCR2, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.