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.

Application

Cystatin C human has been used as a standard in western blot assay. It has also been used to study its effect on the endopeptidase activity of activated Trichobilharzia regenti isoform of cathepsin B1 peptidase (TrCB1).

Biochem/physiol Actions

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). Studies show 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 inhibits transforming growth factor β signaling in normal and cancer cells.

General description

HumanKine human Cystatin C is expressed as a non-glycosylated monomer in human HEK 293 cells. 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 the elimination of small basic peptides or amino acids from the N-terminal end of the protein. This protein is coded by a housekeeping gene, CST3 located on human chromosome 20p11.21 and is generated by nucleated cells.

Legal Information

HumanKine is a registered trademark of Proteintech Group, Inc. and Humanzyme, Inc

Packaging

10 µg in poly bottle

Physical form

Lyophilized from a 0.2 µm filtered solution of 1×PBS