NPL, also known as N-acetylneuraminate lyase, is an enzyme that catalyzes the chemical reaction. (N-acetylneuraminate ->N-acetyl-D-mannosamine + pyruvate) This protein belongs to the family of lyases, specifically the oxo-acid-lyases, which cleave carbon-carbon bonds. It participates in amino sugars metabolism. Recombinant human NPL protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography.