Thermodynamics of unfolding of the all beta-sheet protein interleukin-1 beta

Biochemistry. 1994 Aug 9;33(31):9327-32. doi: 10.1021/bi00197a037.


The thermal denaturation of interleukin-1 beta in solution has been studied by differential scanning calorimetry at various pH values. It is shown that the thermal transition of interleukin-1 beta is completely reversible below pH 2.5, only partly reversible in the pH range 2.5-3.5, and irreversible above pH 3.5. Analysis of the reversible unfolding of interleukin-1 beta shows that the heat denaturation is well approximated by a two-state transition and is accompanied by a significant increase of heat capacity. The partial heat capacity of denatured interleukin-1 beta is very close to that expected for the completely unfolded protein. This permitted us to assign the thermodynamic characteristics of interleukin-1 beta denaturation to its complete unfolding and to correlate them with structural features of the protein. The contributions of hydrogen bonding and hydrophobic interactions to the stability of interleukin-1 beta are analyzed and compared to those for other globular proteins. It is shown that the Gibbs energy of a hydrogen bond in a beta-sheet structure is greater than in alpha-helices.

Publication types

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

MeSH terms

  • Calorimetry, Differential Scanning / methods
  • Cloning, Molecular
  • Escherichia coli
  • Humans
  • Hydrogen Bonding
  • Interleukin-1 / chemistry*
  • Mathematics
  • Models, Theoretical
  • Protein Denaturation*
  • Protein Structure, Secondary*
  • Recombinant Proteins / chemistry


  • Interleukin-1
  • Recombinant Proteins