Identification of an Acidic Dipeptide, β-Aspartylglycine, in the CNS of Aplysia |
| |
Authors: | M W McCaman J Stetzler |
| |
Institution: | Division of Neurosciences, Beckman Research Institute of the City of Hope, Duarte, California U.S.A. |
| |
Abstract: | Abstract: A novel dipeptide, (β-aspartylglycine (β-DG), has been isolated from tissues of the marine gastropod mollusc Aplysia californica. This compound was detected only in Aplysia and not in other molluscs, such as Helix or Mercenaria , or in lobster or frog. Among the Aplysia tissues, the highest levels of β-DG were in nervous tissue and in the reproductive tract. β-DG was assayed by HPLC as the o -phthaldialdehyde derivative and found to be present in all individual, identified neurons at a concentration of approximately 40 pmol/μg protein. The peptide was identified as β-DG by gas chromatography-mass spectrometry (GCMS) using trimethylsilyl derivatives prepared before and after acid hydrolysis. It was further characterized as the β-isomer by TLC, including Rf, atypical blue-gray color with ninhydrin, and a violet color with Cu2+-ninhydrin. A fractionation scheme is described whereby acid-soluble tissue constituents can be divided into acidic, neutral, and basic components using mini ion-exchange columns. This partial purification prior to TLC analysis was necessary to remove compounds that interfered with the isolation of β-DG. |
| |
Keywords: | β-Aspartylglycine Peptide Invertebrates Aplysia californica Neuropeptide |
|
|