Recombinant Human Cystatin S Protein (His Tag)

Name: Recombinant Human Cystatin S Protein (His Tag)
Brand: Beta LifeScience
SKU: BLPSN-1538
Availability: InStock

Collections: Other recombinant proteins, Recombinant proteins

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Product Overview

Tag	His
Host Species	Human
Accession	NP_001890.1
Synonym	CST4, MGC71923
Background	Cystatin-S, also known as Cystatin-4, Salivary acidic protein 1, Cystatin-SA-III and CST4, is a secreted protein which belongs to thecystatin 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.
Description	A DNA sequence encoding the human CST4 (NP_001890.1) (Met 1-Ala 141) was fused with a His tag at the C-terminus.
Source	HEK293
Predicted N Terminal	Ser 21
AA Sequence	Met 1-Ala 141
Molecular Weight	The secreted recombinant human CST4 consists of 132 a.a. and migrates as an approximately 16 kDa band in SDS-PAGE under reducing conditions as predicted.
Purity	>98% as determined by SDS-PAGE
Endotoxin	< 1.0 EU per μg of the protein as determined by the LAL method
Bioactivity	Please contact us for detailed information
Formulation	Lyophilized from sterile PBS, pH 7.4.
Stability	The recombinant proteins are stable for up to 1 year from date of receipt at -70°C.
Usage	For Research Use Only
Storage	Store the protein under sterile conditions at -20°C to -80°C. It is recommended that the protein be aliquoted for optimal storage. Avoid repeated freeze-thaw cycles.

FAQs

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Proteins are sensitive to heat, and freeze-drying can preserve the activity of the majority of proteins. It improves protein stability, extends storage time, and reduces shipping costs. However, freeze-drying can also lead to the loss of the active portion of the protein and cause aggregation and denaturation issues. Nonetheless, these adverse effects can be minimized by incorporating protective agents such as stabilizers, additives, and excipients, and by carefully controlling various lyophilization conditions.

Commonly used protectant include saccharides, polyols, polymers, surfactants, some proteins and amino acids etc. We usually add 8% (mass ratio by volume) of trehalose and mannitol as lyoprotectant. Trehalose can significantly prevent the alter of the protein secondary structure, the extension and aggregation of proteins during freeze-drying process; mannitol is also a universal applied protectant and fillers, which can reduce the aggregation of certain proteins after lyophilization.

Our protein products do not contain carrier protein or other additives (such as bovine serum albumin (BSA), human serum albumin (HSA) and sucrose, etc., and when lyophilized with the solution with the lowest salt content, they often cannot form A white grid structure, but a small amount of protein is deposited in the tube during the freeze-drying process, forming a thin or invisible transparent protein layer.

Reminder: Before opening the tube cap, we recommend that you quickly centrifuge for 20-30 seconds in a small centrifuge, so that the protein attached to the tube cap or the tube wall can be aggregated at the bottom of the tube. Our quality control procedures ensure that each tube contains the correct amount of protein, and although sometimes you can't see the protein powder, the amount of protein in the tube is still very precise.

To learn more about how to properly dissolve the lyophilized recombinant protein, please visit Lyophilization FAQs.