Abstract: | Abstract— The subcellular distributions of tyrosine transaminase, DOPA transaminase, tryptophan transaminase and 5-hydroxytryptophan (5-HTP) transaminase were studied in rat brain. - 1 For all of these transaminases 60-81 per cent of the total activities were found in the crude mitochondrial fraction. Tyrosine transaminase was the most active enzyme.
- 2 Tyrosine transaminase and DOPA transaminase had very similar distributions in all fractions, but the distribution of tryptophan transaminase and 5-HTP transaminase differed in the microsomal (Mic) and synaptic vesicle (M2) fractions. Only 5-HTP transaminase was highly concentrated in the M2 fraction.
- 3 DOPA transaminase was inhibited by dopamine and 5-HT, but these compounds had no effect on 5-HTP transaminase. Both enzymes were completely inhibited by m-hydroxybenzoyloxyamine.
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