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> ELISA > ELISA Pair Set > Cystatin S / CST4 ELISA Pair Set, Human ELISA Pair Set Cystatin S / CST4 ELISA Pair Set, Human ELISA Pair Set 
| Catalog | Size (Price) | Quantity | In Stock | Operation | Other Information |
| SEK11542 |
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Human Cystatin S / CST4 ELISA Pair Set
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Order or Inquire for Cystatin S / CST4 ELISA Pair Set |
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High affinity Human Cystatin S / CST4 ELISA Pair Set |
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Detection limit - 2.4 pg/ml |
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Affordable price and 30%-80% cost saving for Bulk order |
- Materials
- Protocol
- Trouble Shooting
- Image & Flash
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No signal |
Incorrect or no Detection Antibody was added |
Add appropriate Detection Antibody and continue |
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Substrate solution was not added |
Add substrate solution and continue |
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Incorrect storage condition |
Check if the kit is stored at recommended condition and used before expiration date |
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Poor Standard Curve |
Standard was incompletely reconstituted or was inappropriately stored |
Aliquot reconstituted standard and store at -70 ℃ |
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Imprecise / inaccurate pipetting |
Check / calibrate pipettes |
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Incubations done at inappropriate temperature, timing or agitation |
Follow the general ELISA protocol |
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Background wells were contaminated |
Avoid cross contamination by using the sealer appropriately |
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Poor detection value |
The concentration of antigen in samples was too low |
Enriching samples to increase the concentration of antigen |
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Samples were ineffective |
Check if the samples are stored at cold environment. Detect samples in timely manner |
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High Background |
Insufficient washes |
Use multichannel pipettes without touching the reagents on the plate |
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Increase cycles of washes and soaking time between washes |
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TMB Substrate Solution was contaminated |
TMB Substrate Solution should be clear and colorless prior to addition to wells |
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Materials were contaminated |
Use clean plates, tubes and pipettes tips |
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Non-specificity |
Samples were contaminated |
Avoid cross contamination of samples |
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The concentration of samples was too high |
Try higher dilution rate of samples |
Problems 
Possible Sources 
Solutions 
Human Cystatin S / CST4 ELISA Pair Set Related Products & Topics
Related Areas:
Proteins:
Antibodies:
Background
Cystatin-S, also known as Cystatin-4, Salivary acidic protein 1, Cystatin-SA-III and CST4, is a secreted protein which belongs to the cystatin family. Cystatin-4 / CST4 is expressed in submandibular and sublingual saliva but not in parotid saliva (at protein level). It is also expressed in saliva, tears, urine and seminal fluid. 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. Cystatin-4 / CST4 strongly inhibits papain and ficin, partially inhibits stem bromelain and bovine cathepsin C, but does not inhibit porcine cathepsin B or clostripain. Papain is inhibited non-competitively. Cystatin-4 / CST4 is an S-type cystatin, based on its high level of expression in saliva, tears and seminal plasma. The specific role in these fluids is unclear but antibacterial and antiviral activity is present, consistent with a protective function.
