Purification, characterization and primary structure of a chymotrypsin inhibitor from Naja atra venom

Comp Biochem Physiol B Biochem Mol Biol. 2004 Feb;137(2):219-24. doi: 10.1016/j.cbpc.2003.11.007.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Chromatography, Liquid
  • Chymotrypsin / chemistry
  • Elapid Venoms / chemistry*
  • Elapidae
  • Molecular Sequence Data
  • Sequence Alignment
  • Sequence Analysis, Protein
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  • Trypsin Inhibitors / chemistry*
  • Trypsin Inhibitors / isolation & purification*

Substances

  • Elapid Venoms
  • Trypsin Inhibitors
  • Chymotrypsin