NMR studies of the solution properties of recombinant murine interleukin-6

Craig J. Morton, Haiping Bai, Annet Hammacher, Raymond S. Norton, Richard J. Simpson, Bridget C. Mabbutt

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The effects of solvent, pH and temperature on the 1H-NMR spectra of recombinant murine interleukin-6 (IL-6) are described. Assignments made from two-dimensional homonuclear spectra are presented for resonances of the fifteen aromatic amino-acid side chains. A time-dependent loss of intensity was observed for all resonances in the spectrum of IL-6, probably as a result of aggregation. This aggregation is markedly temperature-dependent. The pKa values of the four histidine residues in murine IL-6 has been measured; one has a value of 5.5, approx. one pH unit less than the value exhibited by the other three. Analysis of the NOESY spectra has allowed a preliminary characterisation of the nature of interactions among the aromatic side chains within the protein fold. 1H and 15N resonances of residues Thr-4 to Val-21 are assigned from three-dimensional 1H-15N correlated spectroscopy, and evidence is presented for these residues comprising a mobile N-terminal tail with little ordered structure. An N-terminal mutant lacking the first 22 residues of the murine IL-6 sequence and known to possess full biological activity was also examined and shown to have essentially retained the tertiary fold of the native molecule.

Original languageEnglish
Pages (from-to)189-203
Number of pages15
JournalBiochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology
Issue number2
Publication statusPublished - 12 Jun 1995
Externally publishedYes


  • Cytokine structure
  • Interleukin-6
  • Multidimensional NMR
  • Resonance assignment
  • α-helical bundle

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