Thermally induced fibrillar aggregation of hen egg white lysozyme

Biophys J. 2005 Jan;88(1):515-26. doi: 10.1529/biophysj.104.048819. Epub 2004 Oct 15.

Abstract

We study the effect of pH and temperature on fibril formation from hen egg white lysozyme. Fibril formation is promoted by low pH and temperatures close to the midpoint temperature for protein unfolding (detected using far-ultraviolet circular dichroism). At the optimal conditions for fibril formation (pH 2.0, T = 57 degrees C), on-line static light-scattering shows the formation of fibrils after a concentration-independent lag time of approximately 48 h. Nucleation presumably involves a change in the conformation of individual lysozyme molecules. Indeed, long-term circular dichroism measurements at pH 2.0, T = 57 degrees C show a marked change of the secondary structure of lysozyme molecules after approximately 48 h of heating. From atomic force microscopy we find that most of the fibrils have a thickness of approximately 4 nm. These fibrils have a coiled structure with a periodicity of approximately 30 nm and show characteristic defects after every four or five turns.

MeSH terms

  • Animals
  • Cell Nucleus / metabolism
  • Chickens
  • Circular Dichroism
  • Dose-Response Relationship, Drug
  • Egg White*
  • Electrophoresis, Polyacrylamide Gel
  • Hot Temperature
  • Humans
  • Hydrogen-Ion Concentration
  • Hydrolysis
  • Light
  • Microscopy, Atomic Force
  • Muramidase / chemistry*
  • Muramidase / metabolism
  • Protein Conformation
  • Protein Denaturation
  • Protein Folding
  • Protein Renaturation
  • Protein Structure, Secondary
  • Proteins / chemistry
  • Scattering, Radiation
  • Temperature
  • Time Factors

Substances

  • Proteins
  • hen egg lysozyme
  • Muramidase