The cystatin superfamily encompasses proteins that contain multiple cystatin-like sequences. Some of the members are active cysteine protease inhibitors, while others have lost or perhaps never acquired this inhibitory activity. There are three inhibitory families in the superfamily, including the type 1 cystatins (stefins), type 2 cystatins and the kininogens. The type 2 cystatin proteins are a class of cysteine proteinase inhibitors found in a variety of human fluids and secretions, where they appear to provide protective functions. The cystatin locus on chromosome 20 contains the majority of the type 2 cystatin genes and pseudogenes. This gene is located in the cystatin locus and encodes the most abundant extracellular inhibitor of cysteine proteases, which is found in high concentrations in biological fluids and is expressed in virtually all organs of the body. A mutation in this gene has been associated with amyloid angiopathy. Expression of this protein in vascular wall smooth muscle cells is severely reduced in both atherosclerotic and aneurysmal aortic lesions, establishing its role in vascular disease.
Sample Type
Serum, plasma, urine, saliva and tissue homogenates
Intended Use
For the quantitative determination of human cystatin C (Cys-C) concentrations in serum, plasma, urine, saliva and tissue homogenates. Sensitivity
Specificity
This assay has high sensitivity and excellent specificity for detection of human Cys-C. No significant cross-reactivity or interference between human Cys-C and analogues was observed.
Test Principle
This BioAssay™ employs the quantitative sandwich enzyme immunoassay technique. Antibody specific for Cys-C has been pre-coated onto a microplate. Standards and samples are pipetted into the wells and any Cys-C present is bound by the immobilized antibody. After removing any unbound substances, a biotin-conjugated antibody specific for Cys-C is added to the wells. After washing, avidin conjugated Horseradish Peroxidase (HRP) is added to the wells. Following a wash to remove any unbound avidin-enzyme reagent, a substrate solution is added to the wells and color develops in proportion to the amount of Cys-C bound in the initial step. The color development is stopped and the intensity of the color is measured.
Kit Components
Assay plate (12x8 coated Microwells), 1x96 wellstStandard (Freeze dried), 2x vials tBiotin-antibody (100X concentrate), 1x120ul tHRP-avidin (100X concentrate), 1x120ul tBiotin-antibody Diluent, 1x15ml tHRP-avidin Diluent, 1x15ml tSample Diluent, 1x50ml tWash Buffer (25X concentrate), 1x20ml tTMB Substrate, 1x10ml tStop Solution, 1x10ml tAdhesive Strip (For 96 wells), 4x strips tInstruction manual t
Storage and Stability
Store powder at 4°C liquid at -20°C. Store other components at 4°C. Stable for at least 6 months For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap.
