Comparison of alpha-lactalbumin and lysozyme using vibrational circular dichroism. Evidence for a difference in crystal and solution structures

Biochemistry. 1991 Oct 29;30(43):10479-85. doi: 10.1021/bi00107a016.

Abstract

The conformation of the milk protein alpha-lactalbumin has been studied using vibrational circular dichroism (VCD) and compared to parallel studies on lysozyme. These proteins have been shown by Acharya et al. [(1989) J. Mol. Biol. 208, 99-127] to have very similar three-dimensional crystal structures. However, their VCD spectra in D2O solution are quite different. The VCD of lysozyme in D2O more resembles that of alpha-lactalbumin in 33% propanol/D2O, under which conditions alpha-lactalbumin has conformationally transformed to a structure with increased helical fraction. These results can be seen to be consistent with UVCD and resolution-enhanced FTIR spectra of alpha-lactalbumin and lysozyme in both D2O and H2O environments. The solvent sensitivity of the alpha-lactalbumin spectra and hence of its conformation contrasted with the lack of such sensitivity for lysozyme suggest that the alpha-lactalbumin crystal structure represents a conformation different from that which is dominant in aqueous solution.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cattle
  • Chickens
  • Circular Dichroism
  • Crystallization
  • Female
  • Lactalbumin / chemistry*
  • Muramidase / chemistry*
  • Protein Conformation
  • Spectrophotometry, Infrared
  • Vibration

Substances

  • Lactalbumin
  • Muramidase