Human Cystatin A (CSTA 1) also called stefin A, Cystatin AS or keratolinin, is a member of family 1 of the cystatin superfamily, which is characterized by lacking of disulphide bonds and carbohydrates. CystatinA/StefinA is an intracellular inhibitor regulating the activities of cysteine proteases of the papain family such as Cathepsins B, H and L. Cystatin A is also implicatedin a number of disease states.Due to altered proteolytic state in cancer progression, CystatinA may play a role in the proteolitic pathways.Galectin-3, like all galectins, contains a CRD, while having a distinct chimeric structure with an extra N-terminal tail consisting of 8-13 copies of a 9 aa-repeat consensus sequence that is rich in proline, tyrosine, and glycine. Galectin-3 shares sequence similarity with apoptosis suppressor protein Bcl-2, and due to the Bcl-2-like function,it has been associated with the inhibition of apoptosis and tumor progression. Galectin-3 has also been demonstrated to be involved in heart and skin diseases.

·Description
Recombinant Human Cystatin A produced in E. coli is a non-glycosylated polypeptide chain consisting of 98 amino acid residue with an N-terminal Met and having a molecular mass of 11kDa.

·Quality Control

Biological activity: The IC50 value is < 3.4 nM, as measured by its ability to inhibit papain cleavage of a fluorogenic peptide substrate.

Purity: Greater than 98.0% as determined by:
(a) Analysis by RP-HPLC.
(b) Analysis by reducing and non-reducing SDS-PAGE Silver Stained gel.
Amino-Acid Sequence: The sequence of the first five N-terminal amino acids was determined and was found to be Met-Ile-Pro-Gly-Gly.

Endotoxin:Less than 0.1ng/μg (1.0EU/μg) of hCSTA1 as determined by LAL test.

·Formulation
Sterile and Lyophilized aliquots with a 0.2um filtered protein solution containing 50mM Tris pH7.5, 100mM NaCl.
·Reconstitution
It is recommended to reconstitute the lyophilized rHuCSTA1 in sterile buffer 50mM Tris pH7.5, 100mM NaCl with a concentration no less than 100μg/ml, which can then be further diluted to other solutions.

·Storage
Lyophilized rHuCSTA1 although stable at room temperature for 3 weeks, should be stored desiccated below -18°C, which is stable for up to twelve months from date of receipt. Upon reconstitution rHuCSTA1 should be stored at 4°C between 2-7 days and aliquots of reconstituted samples are stable up to 3 months below -18°C for future use.
Please avoid freeze-thaw cycles.