The three-dimensional structure of interleukin-1 beta

The three-dimensional structure of human recombinant interleukin-1 beta has been determined at 0.24 nm resolution by X-ray crystallographic techniques. The partially refined model has a crystallographic R-factor of just under 19%. The structure is composed of 12 beta-strands forming a complex network of hydrogen bonds. The core of the structure can best be described as a tetrahedron whose edges are each formed by two antiparallel beta-strands. The interior of this structure is filled with hydrophobic side-chains. There is a 3-fold repeat in the folding of the polypeptide chain. Although this folding pattern suggests gene triplication, no significant internal sequence homology between topologically corresponding residues exists. The folding topology of interleukin-1 beta is very similar to that described by A. D. McLachlan [(1979) J. Mol. Biol. 133, 557-563] for soybean trypsin inhibitor.