Recombinant human Cystatin S protein

CST4 (Cystatin-S) belongs to the cystatin family. 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. This protein 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. Recombinant human CST4 protein, fused to His-tag at N-terminus, was expressed in E. coli and purified by using conventional chromatography techniques.