title: Stable free-radical forms of plasma proteins or simpler related structures which induce brain excitatory effects.
abstract: Stable free radicals have been prepared from purified plasma proteins, pituitary peptides, and simpler related structures like 5-OH tryptophan and melatonin by oxidation with the free-radical nitrosyl disulfonate in alkaline solution under controlled conditions. The presence of tyrosine or trytophan amino acid residues in the protein was found essential for free-radical formation. These red-colored, stable free radicals showed electron spin resonance spectra in aqueous solutions at room temperature and maintained this characteristic for weeks when stored at 5 degrees C. Illumination, by visible light, of the free-radical proteins and peptides separated from excess nitrosyl disulfonate by salt fractionation or chromatography enhanced the free-radical concentration in the light. The increased signal decayed in the dark. Intravenous administration of the free-radical proteins or peptides into rabbits equipped with chronic cranial electrodes and sedated with a small dose of pentobarbital caused a sudden EEG arousal accompanied by behavioral changes indicative of brain excitation. Illumination of the free-radical compounds prior to administration enhanced the effects. Untreated control proteins or peptides had no effects. The observations are interpreted to suggest the involvement of free-radical structures in the transfer of energy in nervous tissue.
mesh_terms: D006916:5-Hydroxytryptophan / Q000494:pharmacology; D000818:Animals; D001798:Blood Proteins / Q000494:pharmacology*; D001921:Brain / Q000187:drug effects*; D003460:Crystallization; D004569:Electroencephalography; D004578:Electron Spin Resonance Spectroscopy; D004735:Energy Transfer; D005609:Free Radicals / Q000494:pharmacology; D007275:Injections, Intravenous; D008297:Male; D011817:Rabbits; D012709:Serum Albumin / Q000494:pharmacology
chemical_list: D001798:Blood Proteins; D005609:Free Radicals; D012709:Serum Albumin; D006916:5-Hydroxytryptophan