PMID: 20124699

Authors:

Cook WJ, Galakatos N, Boyar WC, Walter RL, Ealick SE

Title:

Structure of human desArg-C5a.

Journal:

Acta Crystallogr D Biol Crystallogr. 2010 Feb;66(Pt 2):190-7. Epub 2010 Jan 22.

Abstract:

The anaphylatoxin C5a is derived from the complement component C5 during activation of the complement cascade. It is an important component in the pathogenesis of a number of inflammatory diseases. NMR structures of human and porcine C5a have been reported; these revealed a four-helix bundle stabilized by three disulfide bonds. The crystal structure of human desArg-C5a has now been determined in two crystal forms. Surprisingly, the protein crystallizes as a dimer and each monomer in the dimer has a three-helix core instead of the four-helix bundle noted in the NMR structure determinations. Furthermore, the N-terminal helices of the two monomers occupy different positions relative to the three-helix core and are completely different from the NMR structures. The physiological significance of these structural differences is unknown.