title: Structure of human desArg-C5a.
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.
authors.affiliation: University of Alabama at Birmingham, Birmingham, AL 35294, USA. wjcook@uab.edu
authors.forename: William J
authors.initials: WJ
authors.lastname: Cook
authors.forename: Nicholas
authors.initials: N
authors.lastname: Galakatos
authors.forename: William C
authors.initials: WC
authors.lastname: Boyar
authors.forename: Richard L
authors.initials: RL
authors.lastname: Walter
authors.forename: Steven E
authors.initials: SE
authors.lastname: Ealick
mesh_terms: D015937:Complement C5a, des-Arginine / Q000737:chemistry* / Q000378:metabolism; D018360:Crystallography, X-Ray; D006801:Humans; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D044087:Receptor, Anaphylatoxin C5a / Q000737:chemistry / Q000378:metabolism
chemical_list: D015937:Complement C5a, des-Arginine; D044087:Receptor, Anaphylatoxin C5a