1. Purification, characterization and primary structure of a chymotrypsin inhibitor from Naja atra venom.
- Author
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Zhou XD, Jin Y, Lu QM, Li DS, Zhu SW, Wang WY, and Xiong YL
- Subjects
- Amino Acid Sequence, Animals, Chromatography, Liquid, Chymotrypsin chemistry, Elapidae, Molecular Sequence Data, Sequence Alignment, Sequence Analysis, Protein, Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization, Elapid Venoms chemistry, Trypsin Inhibitors chemistry, Trypsin Inhibitors isolation & purification
- Abstract
A chymotrypsin inhibitor, designated NA-CI, was isolated from the venom of the Chinese cobra Naja atra by three-step chromatography. It inhibited bovine alpha-chymotrypsin with a Ki of 25 nM. The molecular mass of NA-CI was determined to be 6403.8 Da by matrix-assisted laser-desorption ionization time-of-flight (MALDI-TOF) analysis. The complete amino acid sequence was determined after digestion of S-carboxymethylated inhibitor with Staphylococcus aureus V8 protease and porcine trypsin. NA-CI was a single polypeptide chain composed of 57 amino acid residues. The main contact site with the protease (P1) has a Phe, showing the specificity of the inhibitor. NA-CI shared great similarity with the chymotrypsin inhibitor from Naja naja venom (identities=89.5%) and other snake venom protease inhibitors.
- Published
- 2004
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