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SUBCELLULAR LOCALIZATION OF TRYPTOPHAN‐5‐MONO‐OXYGENASE IN BOVINE PINEAL GLANDS AND RAPHE NUCLEI
Author(s) -
Hori S.,
Kuroda Y.,
Saito K.,
Ohotani S.
Publication year - 1976
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1976.tb05154.x
Subject(s) - raphe , raphe nuclei , enzyme , dithiothreitol , biochemistry , chemistry , biology , microsome , tryptophan , microbiology and biotechnology , chromatography , medicine , serotonin , amino acid , receptor , serotonergic
— Tryptophan‐5‐mono‐oxygenase from both bovine raphe nuclei and pineal glands was activated by preincubation with dithiothreitol and ferrous ion at pH 8.5. The optimum pH for the enzyme activity lies between pH 6.4 and 7.3. Preincubation increased the activity of the enzyme from raphe nuclei by about 20 times in both the homogenate and 105,000 g precipitate prepared from it. Activity in the 105,000 g supernatant fraction was about trebled. Corresponding increases in pineal gland enzyme activity were noted: 100 times in homogenate and 105,000 g precipitate and 15 times in 105,000 g supernatant fluid. Total recoveries of activated enzyme from the homogenate prepared in hypo‐osmotic medium, in the 105,000 g supernatant and precipitate, were 87.1% and 79.0% for raphe nuclei and pineal glands respectively. Of this, 89.5‐91.3% in the case of the raphe nuclei and 76.0‐82.0% in the case of the pineal glands, was found in the precipitate. In contrast, 85‐90% of the lactate dehydrogenase activity was found in the supernatant fraction. The results of subcellular fractionation revealed that the raphe nuclear enzyme was located in both ‘mitochondrial’ and ‘microsomal’ fraction while the pineal gland enzyme was effectively restricted to the ‘mitochondrial’ fraction. The structural characteristics of the fraction were confirmed by electron microscopy.