The mechanism of 2,2,2-trichloroacetic acid-induced protein precipitation

J Protein Chem. 1997 May;16(4):291-7. doi: 10.1023/a:1026357009886.

Abstract

The mechanism of 2,2,2-trichloroacetic acid (TCA)-induced precipitation of proteins is studied. The TCA-induced protein precipitation curves are observed to be U-shaped. It is bound that the protein-precipitate-inducing effects of TCA are due to the three chloro groups in the molecule. Using cardiotoxin III (CTX III) isolated from the Taiwan cobra (Naja naja atra), as a model protein, we attempt to understand the molecular basis for the TCA-induced effects. Employing circular dichroism, proton-deuterium exchange in conjunction with conventional 2D NMR techniques, and 1-anilino naphthalene-8-sulfonate-binding experiments, we demonstrate that CTX III is in a partially structured state similar to the 'A state' in 3% w/v TCA. It is postulated that the formation of this 'sticky' partial structured 'A state' in the TCA-induced unfolding pathway is responsible for the acid-induced protein precipitation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chemical Precipitation
  • Circular Dichroism
  • Cobra Cardiotoxin Proteins / chemistry
  • Elapid Venoms / chemistry
  • Magnetic Resonance Spectroscopy
  • Muramidase / chemistry
  • Muramidase / drug effects
  • Protein Denaturation / drug effects
  • Protein Folding
  • Proteins / chemistry*
  • Proteins / drug effects*
  • Serum Albumin, Bovine / chemistry
  • Serum Albumin, Bovine / drug effects
  • Trichloroacetic Acid / pharmacology*

Substances

  • Cobra Cardiotoxin Proteins
  • Elapid Venoms
  • Proteins
  • cardiotoxin III, Naja naja atra
  • Serum Albumin, Bovine
  • Trichloroacetic Acid
  • Muramidase