title: Characterization of the physicochemical parameters of dense core atrial gland and lucent red hemiduct vesicles in Aplysia californica.
abstract: Characterizing femtoliter-volume cellular organelles requires innovative analytical techniques such as mass spectrometry, separations, and NMR. The capabilities of all three are demonstrated for characterizing the physicochemical properties of the electron-dense core atrial gland vesicles from Aplysia californica and comparing them with the same properties of the electron lucent red hemiduct vesicles. Single-vesicle mass spectrometric measurements show that the atrial gland vesicles contain an abundance of peptides while the red hemiduct vesicles contain no detectable peptide signals. Capillary electrophoresis with wavelength-resolved native fluorescence detection is used to characterize larger vesicle samples for tyrosine- and tryptophan-containing peptides. Using NMR spectroscopy, we show that the physiologically active peptides located in the core of the atrial gland vesicles are NMR inactive when the vesicles are intact. Resonances from these peptides appear after vesicle lysis by heating, suggesting that initially they are packed in a crystalline or semicrystalline core so that the NMR resonances are not detectable. In contrast, the red hemiduct vesicles appear to have their contents stored in a completely mobile form due to the fact that no new NMR resonances are detected after heating.
authors.affiliation: Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, 1406 West Green Street, Urbana, Illinois 61801, USA.
authors.forename: Luisa
authors.initials: L
authors.lastname: Ciobanu
authors.forename: Stanislav S
authors.initials: SS
authors.lastname: Rubakhin
authors.forename: Jeffrey N
authors.initials: JN
authors.lastname: Stuart
authors.forename: Robert R
authors.initials: RR
authors.lastname: Fuller
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Webb
authors.forename: Jonathan V
authors.initials: JV
authors.lastname: Sweedler
mesh_terms: D000818:Animals; D001048:Aplysia / Q000737:chemistry*; D019075:Electrophoresis, Capillary / Q000379:methods; D005088:Exocrine Glands / Q000737:chemistry* / Q000502:physiology*; D066298:In Vitro Techniques; D013058:Mass Spectrometry / Q000379:methods; D008854:Microscopy, Electron / Q000379:methods; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D022142:Secretory Vesicles / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure; D022161:Transport Vesicles / Q000737:chemistry* / Q000502:physiology* / Q000648:ultrastructure