Redfield C, Smith L J, Boyd J, Lawrence G M, Edwards R G, Smith R A, Dobson C M
Inorganic Chemistry Laboratory, University of Oxford, England.
Biochemistry. 1991 Nov 19;30(46):11029-35. doi: 10.1021/bi00110a004.
Human interleukin 4 (IL-4) has been studied by 2D and 3D NMR techniques using uniformly 15N-labeled recombinant protein. Assignment of resonances for all but 3 of the 130 residues of the recombinant protein has been achieved, enabling the secondary structure of the protein to be defined. This consists of four major alpha-helical regions and one short section of double-stranded antiparallel beta-sheet. Analysis of distance and angle restraints derived from NMR experiments has enabled the overall molecular topology to be determined. This is related to that found for other four-helix proteins but has several distinctive features including cross-linking of helices by means of three disulfide bonds and a short section of beta-sheet. The structural analysis gives support to the hypothesis that many helical cytokines have a common fold and provides a basis for understanding the biological function of IL-4.
