Mechanism of irreversible inactivation of phenylalanine-4- and tryptophan-5-hydroxylases by (4-/sup 36/Cl, 2-/sup 14/C)p-chlorophenylalanine: a revision
Intraperitoneal injection of (4-/sup 36/Cl, 2-/sup 14/C)p-chlorophenylalanine (pCPA) (300 mg/kg) in rats revealed absence of chlorine in pure hepatic phenylalanine hydroxyase, while the carbon label appeared a 1--4 moles/mole of (/sup 14/C)tyrosine in the inactivated phenylalanine and cerebral tryptophan-5-hydroxylase. Crystalline muscle aldolase and tyrosine hydroxylase also revealed the presence of (2-/sup 14/C)tyrosine from (2-/sup 14/C)pCPA without inactivating these enzymes. Injection of L-((U)-/sup 14/C) tyrosine led to its incorporation into the above enzymes, but to a different degree without altering the enzyme activity. Repeated injections of p-chlorophenylacetic acid had no effect on phenylalanine or tryptophan-hydroxylase, Administration of pCPA did not change the levels of cerebral biopterins. Reexamination of the effect of cycloheximide on reversing enzymic inactivation by pCPA failed to confirm our earlier observation.
- Research Organization:
- Department of Psychiatry College of Medicine, University of Iowa, Iowa City
- OSTI ID:
- 6781374
- Journal Information:
- Neurochem. Res.; (United States), Vol. 7:1
- Country of Publication:
- United States
- Language:
- English
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TRACER TECHNIQUES
CHLORINE 36
HYDROXYLASES
ENZYME ACTIVITY
BIOLOGICAL PATHWAYS
PHENYLALANINE
RATS
TYROSINE
AMINO ACIDS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBOXYLIC ACIDS
CHLORINE ISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
ENZYMES
HYDROXY ACIDS
ISOTOPE APPLICATIONS
ISOTOPES
LABELLED COMPOUNDS
LIGHT NUCLEI
MAMMALS
NUCLEI
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDOREDUCTASES
RADIOISOTOPES
RODENTS
VERTEBRATES
YEARS LIVING RADIOISOTOPES
550201* - Biochemistry- Tracer Techniques
551001 - Physiological Systems- Tracer Techniques