Additional file 1: of Ancient role of vasopressin/oxytocin-type neuropeptides as regulators of feeding revealed in an echinoderm

Determination of the structure of asterotocin in A. rubens using mass spectrometry (A). LC-ESI-MS/MS analysis of a synthetic peptide (CLVQDCPEG-NH2) with the predicted structure of asterotocin reveals that it elutes with a retention time of 29.8 min and the deconvoluted, monoisotopic, singly charged spectrum derived from MS/MS data for this peptide reveals a singly charged species at a m/z of 960.39, consistent with the expected molecular mass. (B) LC-ESI-MS/MS analysis of an extract of A. rubens radial nerve cords reveals the presence of a peptide with identical retention time and a spectrum that is very similar to synthetic asterotocin. Accurate mass measurement of the singly charged species of the peptide was determined and mass error observed was 0.0002 Da (0.21 ppm). (TIF 9763 kb)