YAEFLa, but not YdAEFLa, is detected using LC-MS to analyze A. californica cerebral ganglia peptide extracts.
A, solid arrow points to the retention time for YAEFLa, and dotted arrow points to the retention time for YdAEFLa. Although the separation in A used a C18 column, the retention times were too close for confident assignment, and a hypercarb column was used as the stationary phase for the separations in B, where the solid arrow points to a peak matching the retention time of the YAEFLa standard (37.7 min) and the dotted arrow points to a retention time expected for YdAEFLa (41.0 min), although no m/z 641.3 is observed at the mass spectrum at this retention time. C, MS/MS fragmentation spectrum of YAEFLa. D, MS/MS fragmentation spectrum of synthetic YAEFLa (37.7 min). E, MS/MS fragmentation spectrum of synthetic YdAEFLa (41.0 min). The MS/MS fragmentation pattern of the endogenous YAEFLa matches the expected fragmentation pattern of Y(l/d)AEFLa at a retention time matching the YAEFLa standard, confirming that this peptide is predominantly in the all l-form.