A non-native alpha-helix is formed in the beta-sheet region of the molten globule state of canine milk lysozyme

Protein J. 2004 Jul;23(5):335-42. doi: 10.1023/b:jopc.0000032653.30096.41.

Abstract

The native and the molten globule states (N and MG states, respectively) of canine milk lysozyme (CML) were examined by CD spectroscopy and AGADIR algorithm, a helix-coil transition program. It revealed that the helical content of the MG state was higher than that of the N-state, suggesting that non-native alpha-helix is formed in the MG state of CML. Using AGADIR, it indicated the possibility of alpha-helix formation in the third beta-strand region in the MG state. To investigate this possibility, we designed a mutant, Q58P, in which the helical propensity of the MG state was significantly decreased around the third beta-strand region. It appeared that the absolute ellipticity value at 222 nm of the mutant in the MG state was smaller than that of the wild-type protein. It could be assumed that the non-native alpha-helix is formed around the third beta-strand region of wild-type CML in the MG state.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Algorithms*
  • Amino Acid Substitution / genetics*
  • Animals
  • Circular Dichroism
  • Dogs
  • Milk / enzymology*
  • Muramidase / chemistry*
  • Muramidase / genetics
  • Point Mutation / genetics*
  • Protein Denaturation / genetics
  • Protein Folding*
  • Protein Structure, Secondary

Substances

  • Muramidase