Modulation of tryptophan hydroxylase stability: a possible mechanism for monoamine enzyme regulation
The instability of brain tryptophan hydroxylase (tryptophan5-monooxygenase: E.C.18.104.22.168), the rate-limiting enzyme in the biosynthesis of serotonin, has been a bane to those workers who have attempted to study this enzyme in both crude and enriched preparations. At present no satisfactory purification procedure exists that yields stable enzyme in relatively abundant amounts. As a consequence, much remains to be understood about this important regulatory enzyme. Regarding the lability of tryptophan hydroxylase (TPOH) less as an impediment to our understanding of serotonergic systems and more as a source of understanding, I have begun a study of TPOH that focuses on the stability properties of this enzyme. I review here some of the salient features of this work, which suggest that stability may be yet another regulatable property of tryptophan hydroxylase and may represent a hitherto unrecognized but important mechanism for the control of transmitter levels in the neuron.
KeywordsMagnesium Hydroxyl Tyrosine Amide Adenosine
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