Using evolved pyrrolysyl-tRNA synthetase-tRNA(CUA)(Pyl) pairs, L-phenylalanine, p-iodo-L-phenylalanine and p-bromo-L-phenylalanine have been genetically incorporated into proteins at amber mutation sites in E. coli.

BACKGROUND Women with untreated phenylketonuria (PKU) often have poor reproductive outcomes. OBJECTIVE We assessed the effects of intakes of major nutrients on plasma phenylalanine concentrations and we measured phenylalanine hydroxylase activity and phenylalanine intakes in pregnant women with PKU. DESIGN Dietary intakes and plasma phenylalanine concentrations were compared in 4 subject gr...

Cloning and expression of the L-phenylalanine dehydrogenase gene, from B. sphaericus in E. coli were done. The gene was cloned in the vector pET16b and transformed into E. coli BL21 (DE3). The functional form of the L-phenylalanine dehydrogenase enzyme was purified by affinity purification techniques, taking advantage of the ability of this enzyme to bind to the nucleotide site affinity dye, Re...

Enzymatic cycling assays for the determination of L-phenylalanine and phenylpyruvate in deproteinized tissue extracts are described. Assay 1 couples glutamine transaminase K with L-phenylalanine dehydrogenase. Assay 2 combines phenylalanine dehydrogenase, L-amino acid oxidase, and catalase. In both assays, tyrosine and some other amino acids (or their alpha-keto acid analogs) can replace phenyl...

To establish an advantageous method for the production of l-amino acids, microbial isomerization of d- and dl-amino acids to l-amino acids was studied. Screening experiments on a number of microorganisms showed that cell suspensions of Pseudomonas fluorescens and P. miyamizu were capable of isomerizing d- and dl-phenylalanines to l-phenylalanine. Various conditions suitable for isomerization by...

A patient with atypical phenylketonuria (defective BH2 synthesis), detected at age 6 months because of severe muscle hypotonia and serum phenylalanine of 20 mg/100 ml, had normal activities of phenylalanine-4-hydroxylase and DHPR in liver biopsy, but only 2% activity in the phenylalanine-4-hyroxylase in vivo test using deuterated phenylalanine. After IV administration of 2.5 mg/kg chemically pu...

Melphalan, also known as L-phenylalanine mustard, phenylalanine mustard, L-PAM, or L-sarcolysin, is a phenylalanine derivative of nitrogen mustard. Melphalan is a bifunctional alkylating agent that is active against selected human neoplastic diseases. The chemical name for melphalan, is 4-bis (2-chloroethyl) amino-L-phenylalanine, it has a molecular weight of 305.20, and its molecular formula i...

Phenylalanine hydroxylase was shown to be inhibited by oudenone and its derivatives in vitro. At a concentration of 2.3 x 10(-3) M, oudenone inhibited phenylalanine hydroxylase by 50%, and some of the oudenone derivatives showed more potent inhibition. The kinetic data have shown that the inhibition by oudenone is competitive with a tetrahydropterin cofactor (6,7-dimethyltetrahydropterin, DMPH4...

Phenylketonuria is caused by mutations in the enzyme phenylalanine hydroxylase gene, that can result in abnormal concentrations of phenylalanine on blood, resulting in metabolites that can cause brain damage. The treatment is based on dietary restriction of phenylalanine, and noncompliance with treatment may result in damage of the brain function. Brain abnormalities can be seen on magnetic res...