The three dimensional structure of rat cytokine CINC/Gro in solution by homonuclear 3D NMR

The solution conformation of rat cytokine‐induced neutrophil chemoattractant (CINC/Gro), a small protein consisting of 72 amino acid residues with proinflammatory activities, and a member of the interleukin 8 family corresponding to a counterpart of human Gro, was investigated with homonuclear 2D and 3D NMR spectroscopy. At each phase of the structural analysis, the homonuclear 3D NOESY‐HOHAHA and HOHAHA‐NOESY spectra afforded valuable data, removing ambiguities intractable by conventional 2D NMR techniques. CINC/Gro exists as a dimer in solution and contains a triple stranded anti‐parallel β‐sheet and C‐terminal α‐helix in the monomer structure, as observed in human IL‐8, but non‐trivial differences are also observed.