Purity: ≥95% (SDS-PAGE)
Application: Cystatin C is an inhibitor of cysteine proteases including cathepsin B (which has been identified as the most important β-amyloid-degrading enzyme. Measurement of cystatin C in serum is replacing creatinine as an indicator of kidney function (glomerular filtration rate, GFR).
General description: HumanKine human Cystatin C is expressed as a non-glycosylated monomer in human HEK 293 cells and has an apparent molecular mass of 12-13 kDa. Cystatin C belongs to the cystatin superfamily. Two isoforms (pI = 7.8, 9.2) of native Cystatin C are found in human urine differentiated by elimination of small basic peptides or amino acids from the N-terminal end of protein. Cystatin C is used as a biomarker of kidney function. 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, such as Alzheimer′s disease. Cystatin C was reported to antagonize transforming growth factor β signaling in normal and cancer cells.
Analysis Note: The inhibitory function of cystatin c on papain’s protease activity was measured by a colorimetric assay using L-BAPA as substrate. IC50 value was measured at 5 to 20 μg/mL (0.3 to 1.5 μM) with a range of 1.56 μg/mL to 50 μg/mL cystatin C in presence of 0.55 μM papain and 0.44 μM L-BAPA.
Preparation Note: This product is lyophilized from a PBS solution. IC50: 0.3-1.5 microM.
Legal Information: HumanKine is a registered trademark of HumanZyme Inc.
Empirical Formula (Hill Notation): C3H6Br2O