Abstract
l-Ascorbate stimulates the enzymic hydroxylation of phenylalanine in vitro by recycling tetrahydrobiopterin, which reduces O(2) utilized in the reaction. It is suggested that ascorbate might have a similar function in vivo; this would explain the apparent regulation of tyrosine hydroxylase and tryptophan hydroxylase activities by this vitamin.
MeSH terms
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Animals
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Ascorbic Acid / pharmacology*
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Ascorbic Acid / physiology
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Carbon Isotopes
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Catecholamines / biosynthesis*
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Female
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Liver / enzymology
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NADP
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Oxidation-Reduction
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Phenylalanine Hydroxylase / metabolism*
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Pteridines
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Rats
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Time Factors
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Tryptophan Hydroxylase / metabolism
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Tyrosine
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Tyrosine 3-Monooxygenase / metabolism
Substances
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Carbon Isotopes
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Catecholamines
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Pteridines
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Tyrosine
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NADP
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Phenylalanine Hydroxylase
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Tyrosine 3-Monooxygenase
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Tryptophan Hydroxylase
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Ascorbic Acid