The regulation of tyrosine production in the anthramycin-producing organism Streptomyces refuineus var. thermotolerans has been studied with wild-type and tyrosine auxotrophic organisms. Growth of the auxotroph on minimal medium plus phenylalanine suggested that phenylalanine may increase the supply of tyrosine. In incubation with whole cells, tyrosine levels increased in response to added phen...

objective electroencephalogram (eeg) is an easy and non invasive evaluation method for diagnosis and early prognosis in children. our aim was to assess the association between eeg and the patients' developmental quotient (dq) level in phenylketonuria. materials & methods in this study, 94 pku patients (45 boys, 49 girls; mean age: 8.5 6.2 years) who were diagnosed through newborn screening test...

Abstract ( R ) - mandelic acid is an industrially important chemical, especially used for producing antibiotics. Its chemical synthesis often uses highly toxic cyanide to produce its racemic form, followed by kinetic resolution with 50% maximum yield. Here we report a green and sustainable biocatalytic method )-mandelic from easily available styrene, biobased L- phenylalanine, renewable feedsto...

The pH optimum of rat liver phenylalanine hydroxylase is dependent on the structure of the cofactor employed and on the state of activation of the enzyme. The tetrahydrobiopterin-dependent activity of native phenylalanine hydroxylase has a pH optimum of about 8.5. In contrast, the 6,7-dimethyltetrahydropterin-dependent activity is highest at pH 7.0. Activation of phenylalanine hydroxylase eithe...

The enzymatic oxidation of phenylalanine to tyrosine has been studied as part of an investigation of the intermediates and enzyme systems involved in the biosynthesis of epinephrine. Womack and Rose (1) indicated that phenylalanine was converted to tyrosine in viva by showing that tyrosine is not essential when sufficient phenylalanine is available. Definite proof was provided by Moss and Schoe...

Kinetic analyses of the irreversible inhibition of L-tyrosine and L-phenylalanine transport in Bacillus subtilis by phenylalanine chloromethyl ketone revealed that the inhibition was due to an affinity labeling process. Phenylalanine chloromethyl ketone is a competetive inhibitor of L-tyrosine and L-phenylalanine transport. The K, values for irreversible inhibition of L-tyrosine and L-phenylala...

Dietary restriction of phenylalanine is the main treatment for phenylketonuria (PKU), and current estimates of requirements are based on plasma phenylalanine concentration and growth. The present study aimed to determine more precisely the phenylalanine requirements in patients with the disease by use of indicator amino acid oxidation, with L-[1-13C]lysine as the indicator. Breath 13CO2 product...