CST5 Human
Sf9, Baculovirus cells.
Description
CST5 Human Recombinant produced in Sf9 Baculovirus cells is a single, glycosylated polypeptide chain containing 123 amino acids (26-142 a.a) and having a molecular mass of 14.36kDa. CST5 is fused to a 6 amino acid His-tag at C-terminus & purified by proprietary chromatographic techniques.
Product Specs
Sf9, Baculovirus cells.
Product Science Overview
Cystatin 5, also known as Cystatin-D or CST5, is a member of the cystatin superfamily. This superfamily includes proteins that contain multiple cystatin-like sequences. Some members of this family are active cysteine protease inhibitors, while others have lost or possibly never had this inhibitory activity. The cystatin superfamily is divided into three inhibitory families: type 1 cystatins (stefins), type 2 cystatins, and kininogens.
Cystatin 5 is a type 2 cystatin protein, which is a class of cysteine proteinase inhibitors found in various human fluids and secretions. The human recombinant form of Cystatin 5 is produced in different expression systems, such as Sf9 Baculovirus cells and HEK293 cells. The recombinant protein typically consists of a single, glycosylated polypeptide chain containing 123 amino acids, with a molecular mass of approximately 14.36 kDa .
The recombinant Cystatin 5 produced in Sf9 Baculovirus cells is fused to a 6 amino acid His-tag at the C-terminus and purified using proprietary chromatographic techniques . Similarly, the recombinant protein produced in HEK293 cells is expressed with a sequence (Gly21-Val142) of human Cystatin D, also fused with a 6×His tag at the C-terminus .
Cystatin 5 functions as a cysteine protease inhibitor. Its inhibitory activity is measured by its ability to inhibit the protease activity of papain, a cysteine protease. The IC50 value of Cystatin 5 is less than 2.0 nM, indicating its high potency as an inhibitor . The inhibitory function is typically assessed using a fluorometric assay with a specific substrate at a defined pH and temperature .
Recombinant Cystatin 5 is primarily used for laboratory research purposes. It is not intended for use as a drug, agricultural or pesticidal product, food additive, or household chemical . The protein is supplied as a sterile filtered clear solution, formulated in phosphate-buffered saline (pH 7.4) with 10% glycerol for stability .
For short-term storage (2-4 weeks), Cystatin 5 should be kept at 4°C. For longer periods, it is recommended to store the protein frozen at -20°C. To ensure long-term stability, adding a carrier protein such as 0.1% human serum albumin (HSA) or bovine serum albumin (BSA) is advisable. It is important to avoid multiple freeze-thaw cycles to maintain the protein’s integrity .
