Erythrocruorin subunits of Perinereis cultrifera Grube (Annelida, Polychaeta) compared with other erythrocruorins

Abstract Polyacrylamide gel electrophoresis (PAGE) in sodium dodecyl sulphate (SDS) shows that Perinereis cultrifera Grube erythrocruorin dissociates into five components with relative mass (Mr) of 13 300, 15 000, 54 000, 61 000, 65 000. The presence of 2-mercaptoethanol in SDS PAGE induces further dissociation: the component with Mr 54 000 gives rise to a new small subunit with M, of 16 200, while the 61000 and 65 000 components dissociate into subunits with Mr of 33 500 and 37 000, respectively. Urea PAGE of the erythrocruorin results in the separation of five bands: the cathodic bands with the highest mobilities correspond to the 16 200, 15 000 and 13 300 subunits, respectively. The erythrocruorin dissociated at alkaline pH, and subjected to SDS PAGE in the presence of 2-mercaptoethanol, dissociates completely into low molecular mass subunits. Amino end group analysis of the erythrocruorin indicates the presence of arginine, lysine, aspartic and glutamic acids. The amino acid composition shows a high c...