Model structures and action of interleukin 1 and its antagonist.

A comparison has been made between the homology and hydrophobicity profiles of six interleukin amino acid sequences and that of the human interleukin 1 beta (IL-1 beta) for which a crystal structure exists. The resulting sequence alignment was used to build model structures for the sequences for three IL-1 alpha, two IL-1 beta and an interleukin receptor antagonist. Analysis of these structures demonstrates that the interleukin molecule has a strong electric dipole which is generated by the topological position of the amino acids in the sequence. Electrostatic surface calculations implicate a particular residues (Lys145) as being fundamental to interleukin activity and this supports site-directed mutation evidence that this residue is required for activity.