CST4, also known as Cystatin-S, belongs to the cystatin family. It 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. This protein is 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. Source: Recombinant protein corresponding to aa21-141 from human CST4, fused to His-tag at C-terminal expressed in insect cell. Molecular Weight: ~15.4kD (131aa) Amino Acid Sequence: ADPMSSSKEE NRIIPGGIYD ADLNDEWVQR ALHFAISEYN KATEDEYYRR PLQVLRAREQ TFGGVNYFFD VEVGRTICTK SQPNLDTCAF HEQPELQKKQ LCSFEIYEVP WEDRMSLVNS RCQEAHHHHH H Storage and Stability: May be stored at 4C for short-term only. Aliquot to avoid repeated freezing and thawing. Store at -20C. Aliquots are stable for 6 months after receipt at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.
