CST3 Human, His Active
Description
2.1. Protease Inhibition and Vascular Biology
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CST3 inhibits cysteine proteases (e.g., cathepsins B, L, S) by forming tight complexes, modulating extracellular matrix remodeling .
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In vascular endothelial cells (HUVECs, RBMECs), CST3 suppresses proliferation, migration, and tube formation, suggesting anti-angiogenic properties .
2.2. Diagnostic and Therapeutic Applications
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Renal Function: Superior to creatinine in estimating glomerular filtration rate (GFR), with high sensitivity for early-stage kidney disease .
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Cardiovascular Disease: Low CST3 levels correlate with atherosclerosis and aortic aneurysms due to dysregulated elastin degradation .
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Cancer and Neurodegeneration: Elevated in malignancies and implicated in amyloidosis (e.g., Alzheimer’s disease) via β-amyloid interactions .
3.1. Biochemical Stability
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Storage: Lyophilized protein remains stable at -20°C long-term; reconstituted solutions tolerate 4°C for 1–2 weeks .
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Formulation: Typically buffer-exchanged into Tris-HCl (pH 7.5–8.0) or HEPES with NaCl and glycerol .
| Parameter | Recommendations | Source |
|---|---|---|
| Reconstitution | 0.1–1.0 mg/mL in sterile water or PBS | |
| Carrier Proteins | 0.1% HSA/BSA recommended for long-term storage to prevent aggregation |
4.1. Expression Systems
| Host | Advantages | Disadvantages |
|---|---|---|
| E. coli | High yield, cost-effective | Lacks post-translational modifications |
| HEK293 | Proper folding, glycosylation possible | Lower yield, higher cost |
| Pichia pastoris | Scalable, suitable for secretion | Longer production time |
4.2. Clinical Relevance
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Renal Biomarker: Serum CST3 detects subclinical kidney dysfunction with AUC >0.90 vs. creatinine (AUC ~0.75) .
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Vascular Studies: CST3 knockout models exhibit accelerated atherosclerosis in mice .
Ongoing Research Directions
Product Specs
Cystatin C belongs to the cystatin family, a group of proteins with cystatin-like sequences. Some cystatins are active cysteine protease inhibitors, while others have lost or never possessed this ability. The cystatin family is further divided into three subtypes: type 1 cystatins, type 2 cystatins, and kininogens. Chromosome twenty houses the locus for most type 2 cystatin genes, including the gene for Cystatin C. Cystatin C is the most abundant extracellular inhibitor of cysteine proteases, widely distributed in biological fluids and present in all tissues.
Recombinant human CST3, produced in E. coli, is a single, non-glycosylated polypeptide chain. It comprises 141 amino acids (residues 27-146), has a molecular weight of 15.6 kDa, and includes a 21 amino acid His tag at the N-terminus. Purification is achieved using proprietary chromatographic methods.
The CST3 solution (0.25mg/ml) is formulated in a buffer containing 0.1M NaCl, 20mM Tris-HCl (pH 8.0), and 20% glycerol.
For short-term storage (2-4 weeks), keep at 4°C. For extended periods, store frozen at -20°C. The addition of a carrier protein (0.1% HSA or BSA) is recommended for long-term storage. Avoid repeated freeze-thaw cycles.
Purity is determined to be greater than 95.0% by SDS-PAGE analysis.
The IC50 value, determined by a fluorometric assay using Z-FR-AMC as the substrate at pH 7.5 and 25°C, is less than 2.0 nM. This indicates strong inhibitory activity of Cystatin 3 against the protease papain.
Cystatin-C, Cystatin-3, Neuroendocrine basic polypeptide, Gamma-trace, Post-gamma-globulin, CST3, MGC117328.
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Product Science Overview
Cystatin C is a small, non-glycosylated protein that belongs to the cystatin superfamily. This family of proteins is known for their ability to inhibit cysteine proteases, which are enzymes that break down proteins. Cystatin C is particularly important due to its role in various physiological and pathological processes, including inflammation, tumor invasion, and neurological diseases .
Cystatin C is composed of 120 amino acids and has a molecular weight of approximately 13 kDa. It is ubiquitously expressed in human tissues and body fluids, making it a valuable biomarker for various diseases. The protein inhibits several cysteine proteases, including papain and cathepsins B, H, K, L, and S .
The recombinant form of Cystatin C, often tagged with a histidine (His) tag for purification purposes, is produced in various expression systems, including E. coli and mammalian cells. The His tag allows for easy purification using nickel affinity chromatography, ensuring high purity and activity of the protein .
Recombinant Cystatin C retains its ability to inhibit cysteine proteases, making it a useful tool in research and therapeutic applications. The protein’s inhibitory activity is measured by its ability to prevent the cleavage of specific peptide substrates by cysteine proteases. For instance, the inhibition of papain-induced cleavage of a fluorogenic peptide substrate is a common assay used to determine the activity of recombinant Cystatin C .
- Research: Cystatin C is widely used in research to study its role in various biological processes and diseases. Its inhibitory activity against cysteine proteases makes it a valuable tool for investigating the mechanisms of protease regulation and the development of protease inhibitors.
- Clinical Diagnostics: Due to its stable expression in body fluids, Cystatin C is used as a biomarker for kidney function. Elevated levels of Cystatin C in the blood are indicative of impaired kidney function and are used to diagnose and monitor chronic kidney disease.
- Therapeutics: The protein’s ability to inhibit cysteine proteases has potential therapeutic applications. For example, Cystatin C could be used to develop treatments for diseases characterized by excessive protease activity, such as certain cancers and inflammatory conditions .
