The transamination by pig mitochondrial and supernatant aspartate transaminase of aromatic amino acids was studied in order to determine if an analogy exists between these enzymes and a previously reported brain phenylalanine transaminase (GEORGE, H., AND GABAY, S. (1968) Biochim. Biophys. Ada, 167, 555). Supernatant and mitochondrial aspartate transaminase from pig heart can utilize aromatic a...

This work had two purposes: (i) to determine in vivo whether liver phenylalanine hydroxylase (PAH) is regulated by its substrates phenylalanine and tetrahydrobiopterin (BH4) as studies with purified enzyme suggest and (ii) to investigate in vivo the relationship between PAH activity and BH4 turnover. We found there are two BH4 pools in hepatocytes, one that is metabolically available (free BH4)...

Phenylalanine hydroxylase, the enzyme that catalyzes the irreversible hydroxylation of phenylalanine to tyrosine, was purified from rat kidney with the use of phenyl-Sepharose, DEAE-Sephacel, and gel permeation high pressure liquid chromatography. Our most highly purified fractions had a specific activity in the presence of 6-methyltetrahydropterin, of 1.5 mumol of tyrosine formed/min/mg of pro...

The amino acid antimetabolite, DL-p-fluorophenylalanine (FPA), inhibited induction of flowering in the short-day cocklebur plant, Xanthium pensylvanicum Wall., primarily by interfering with processes occurring during the inductive dark period. At the concentrations used the inhibitor had little effect on subsequent vegetative development of the plant.The inhibition was largely reversed (interna...

The inhibitory effects of potassium sorbate on the bioenergetics, phenylalanine uptake, protein synthesis, and certain aspects of cell regulation were examined in putrefactive anaerobe 3679. Undissociated sorbic acid appeared to act as a protonophore by lowering the intracellular pH and dissipating the proton motive force of the membrane. Sorbate inhibited the uptake of phenylalanine, decreased...

To investigate the regulatory interactions of amino acid transport and incorporation, we determined the effects of dipeptides on amino acid uptake by bacteria in an estuary and a freshwater lake. Dipeptides noncompetitively inhibited net transport and incorporation of amino acids into macromolecules but had no effect on the ratio of respiration to incorporation. Nearly maximum inhibition occurr...

338 PRINCIPLE T HE INHIBITION of growth of Bacillus subtilis ATCC 6051 by B-2-thienylalanine in a minimal culture medium is prevented by phenylalanine, phenylpyruvic acid, and phenyllactic acid.l* This finding has permitted the development of a convenient agar diffusion microbial assay for phenylketonuria (PKU), employing small filter paper discs, impregnated with blood or urine, placed upon th...

the purpose of the current research is investigating the phenylalanine removal by using magnetic nanoparticles (fe3o4) from water samples. the effect of ph, contact time and phenylalanine concentration on phenylalanine adsorption efficiency by magnetite nanoparticles are studied in a batch system. transmission electron microscopy (tem), x-ray diffraction patterns (xrd) and fourier transform inf...

An acute administration of phenylalanine to neonatal animals has been reported to result in large decreases in the intracellular concentrations of several essential amino acids in neural tissue, as well as an inhibition of neural protein synthesis. The present report evaluates the effects of the loss of amino acids on the concentrations of aminoacyl-tRNA in vivo, with the view that an alteratio...