title: On the interaction between 5-hydroxytryptamine and N-acetylneuraminic acid under aqueous conditions.
abstract: A complex designated 5-HT-NeuAc was formed between 5-hydroxytryptamine (5-HT) and N-acetylneuraminic acid (NeuAc) under aqueous conditions. Complex formation was encouraged by exposure to light (3000-3800 A; 1 A = 0.1 nm) and freeze-drying and the freeze-dried complex was isolated by gel filtration chromatography. Although stable to rechromatography on Bio-Gel P-2 if H2O was the eluent, 5-HT-NeuAc dissociated into the free components when placed in 0.1 M NaCl. Chemical analyses of the isolated complex showed that an equimolar amount of 5-HT and NeuAc was present and that all group functions were intact; these data suggested that the association between 5-HT and NeuAc was noncovalent. Spectrophotometric measurements demonstrated a small increase (approximately 12%) in extinction coefficient (275 nm) and a large increase (340- to 440-fold) in fluorescence emission (340 nm) compared with 5-HT alone. Data obtained from 1H nuclear magnetic resonance spectroscopy (250 MHz) of 5-HT and NeuAc standards compared closely to published reports. In comparison, measurements made with 5-HT-NeuAc showed that all 5-HT protons were slightly deshielded; of the NeuAc protons, slight deshielding of H8 and significant shielding of H3eq, H3ax, and H6 was observed. From these observations, a model describing the association between 5-HT and NeuAc is proposed.
mesh_terms: D007700:Kinetics; D008027:Light; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D019158:N-Acetylneuraminic Acid; D012701:Serotonin / Q000378:metabolism* / Q000528:radiation effects; D012794:Sialic Acids / Q000378:metabolism* / Q000528:radiation effects; D014867:Water
chemical_list: D012794:Sialic Acids; D014867:Water; D012701:Serotonin; D019158:N-Acetylneuraminic Acid