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. 2013;77(10):2077-81.
doi: 10.1271/bbb.130424. Epub 2013 Oct 7.

Molecular cloning and characterization of cystatin, a cysteine protease inhibitor, from bufo melanostictus

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Free article

Molecular cloning and characterization of cystatin, a cysteine protease inhibitor, from bufo melanostictus

Wa Liu et al. Biosci Biotechnol Biochem. 2013.
Free article

Abstract

Cystatins are efficient inhibitors of papain-like cysteine proteinases, and they serve various important physiological functions. In this study, a novel cystatin, Cystatin-X, was cloned from a cDNA library of the skin of Bufo melanostictus. The single nonglycosylated polypeptide chain of Cystatin-X consisted of 102 amino acid residues, including seven cysteines. Evolutionary analysis indicated that Cystatin-X can be grouped with family 1 cystatins. It contains cystatin-conserved motifs known to interact with the active site of cysteine proteinases. Recombinant Cystatin-X expressed and purified from Escherichia coli exhibited obvious inhibitory activity against cathepsin B. rCystatin-X at a concentration of 8 µM inhibited nearly 80% of cathepsin B activity within 15 s, and about 90% of cathepsin B activity within 15 min. The Cystatin-X identified in this study can play an important role in host immunity and in the medical effect of B. melanostictus.

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