Cystatin C (CST3, Cystatin-3, Gamma-Trace, Neuroendocrine Basic Polypeptide, Post-Gamma-Globulin, Post G-Globulin) is a small molecular weight peptide that is a potent inhibitor of many cysteine proteinases. Because of its small size it is freely filtered by the glomerulus and metabolized after tubular reabsorption. Serum levels of Cystatin C are a more precise test of kidney function than serum creatinine levels. Recently, it has been studied for its role in predicting new-onset or deteriorating cardiovascular disease. It also seems to play a role in brain disorders involving amyloid deposition, such as Creutzfeldt-Jakob disease and Alzheimer’s disease. Human Cystatin C from Molecular Innovations is recombinantly produced in insect cell culture and purified by conventional and chelated metal affinity chromatography. Contains a 10X-Histidine tag at the C terminus for purification. It runs as a single band and is >95percent pure by SDS-PAGE. Inhibits activity of the cysteine proteinase papain using the substrate Pyr-Phe-Leu-pNA.