Amino-acid sequence and disulfide linkages of the anaphylatoxin, des-Arg omega-C5a, from porcine serum.

The primary structure of the porcine complement-derived peptide, des-Arg omega-C5a, has been analysed. Des-Arg omega-C5a is the natural secondary product of the activation fragment of the fifth component of complement, C5a, and represents a classical anaphylatoxin. The elaborated amino-acid sequence confirms the structure of porcine C5a proposed earlier by Gerard and Hugli, with one exception. Further, by end-group determination and sequencing of the unreduced core of des-Arg omega-C5a the position of its three disulfide bridges has been determined, now allowing insight into the tertiary structure of des-Arg omega-C5a.