Purification and characterization of three major hemolymph proteins of an insect, Calpodes ethlius (lepidoptera, hesperiidae)

Like many other Lepidoptera, fifth‐stage Calpodes larvae have three major hemolymph proteins. Their molecular weights were estimated by 3‐15% nondenaturing polyacrylamide gel electrophoresis (N‐PAGE) as 470,000 (arylphorin; Ar), 580,000 (storage protein 2; SP2) and 720,000 (storage protein 1; SP1). Carbohydrate is associated with all three, but only Ar has lipid. The three proteins have been purified by preparative N‐PAGE and sodium dodecyl sulfate (SDS)‐polyacrylamide gel electrophoresis. On 3‐15% SDS gels, Ar dissociated into 82,000 M_r subunits, SP2 into 86,000 M_r subunits, and SP1 into both 86,000 and 90,000 M_r subunits. The 470,000 M_r protein is identified as Ar because it is rich in aromatic amino acids. The 580,000 and 720,000 M_r proteins are rich in glycine and are called storage proteins. Electron microscopy of negatively stained preparations shows that each polymer has a different geometrical arrangement of subunits. SP1 is a cube made from eight subunits. SP2 is a hexamer in the form of a pentahedral prism. Ar is probably an octahedron made from six subunits. All three geometrical arrangements could permit the presence of a central carrying space.