Bioactivity
(Cystatin D is a member of family 2 of the cystatin superfamily. In contrast to other members of family 2, Cystatin D has restricted tissue distribution and has been found only in saliva and tears. Two allelic variants (Arg46 and Cys46) are known in the human protein and they are not significantly different in their inhibitory activity against papain and cathepsins B, H, L and S. Recombinant Human Cystatin D corresponds to the Arg46 variant. The functions of Cystatin D are largely unknown. However, Cystatin D has been shown to inhibit coronavirus replication at its physiological concentration (0.121.9 uM) and has been suggested to play a protective role against proteases present in the oral cavity. The activity of recombinant human Cystatin D was measured by its ability to inhibit papain cleavage of a fluorogenic peptide substrate Z-FR-AMC in the assay buffer 50 mM Tris, pH 7.0. Papain was diluted to 500 ug/ml in activation buffer 50 mM Tris, 5 mM DTT, pH 7.0 and incubated at room temperature for 15 minutes. The activated papain was diluted to 100 ug/ml in the assay buffer and 20 ul different concentrations of recombinant human Cystatin D (MW: 17.45 KD) was incubated with 20 ul 100 ug/ml papain at 37 degree C for 10 minutes. Loading 50 uL of the incubated mixtures which were diluted five-fold in assay buffer into empty wells of a plate, and start the reaction by adding 50 uL of 200 uM substrate. Include a substrate blank containing 50 uL of assay buffer and 50 uL of 200 uM substrate. Then read at excitiation and emission wavelengths of 380 nm and 460 nm, respectively, in kinetic mode for 5 minutes. The result was shown in Figure 1 and it was obvious that recombinant human Cystatin D significantly decreased papain activity. The inhibition IC50 was )
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Product Notes
The CST5 cst5 (Catalog #AAA161930) is an Active Protein produced from E Coli and is intended for research purposes only. The product is available for immediate purchase. AAA Biotech's Cystatin 5 (CST5) can be used in a range of immunoassay formats including, but not limited to, Activity Assay, Cell Culture. Researchers should empirically determine the suitability of the CST5 cst5 for an application not listed in the data sheet. Researchers commonly develop new applications and it is an integral, important part of the investigative research process. The amino acid sequence is listed below: Gly21~Val1 42. It is sometimes possible for the material contained within the vial of "Cystatin 5 (CST5), Active Protein" to become dispersed throughout the inside of the vial, particularly around the seal of said vial, during shipment and storage. We always suggest centrifuging these vials to consolidate all of the liquid away from the lid and to the bottom of the vial prior to opening. Please be advised that certain products may require dry ice for shipping and that, if this is the case, an additional dry ice fee may also be required.Precautions
All products in the AAA Biotech catalog are strictly for research-use only, and are absolutely not suitable for use in any sort of medical, therapeutic, prophylactic, in-vivo, or diagnostic capacity. By purchasing a product from AAA Biotech, you are explicitly certifying that said products will be properly tested and used in line with industry standard. AAA Biotech and its authorized distribution partners reserve the right to refuse to fulfill any order if we have any indication that a purchaser may be intending to use a product outside of our accepted criteria.Disclaimer
Though we do strive to guarantee the information represented in this datasheet, AAA Biotech cannot be held responsible for any oversights or imprecisions. AAA Biotech reserves the right to adjust any aspect of this datasheet at any time and without notice. It is the responsibility of the customer to inform AAA Biotech of any product performance issues observed or experienced within 30 days of receipt of said product. To see additional details on this or any of our other policies, please see our Terms & Conditions page.Item has been added to Shopping Cart
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