A human inborn genetic disease, type I phenylketonuria [13] (PKU) is caused by a mutation in the gene encoding the enzyme phenylalanine dehydrogenase necessary to convert L-phenylalanine (L-Phe) to L-tyrosine, (L-Tyr). The accumulated L-Phe is metabolized by enforced side reaction to phenylpyruvate, phenylacetate, and phenyl-L-lactate excreted with urine, Fig. 1. The excess of phenylalanine hin...

IOCHEMICAL investigations of the phenylalanine-tyrosine specific portion of the aromatic pathmway reveal a reaction sequence depicted in Figure 1. Although the organisms studied use similar intermediates to accomplish phenylalanine and tyrosine synthesis, some important functional differences exist. Aerobacter aerogenes and Escherichia coli W possess two molecular forms of chorismate mutase sep...

The effect of gamma irradiation on lignin biosynthesis during wound healing in potato tubers was studied by [U-C] phenylalanine incorporation into lignin and monitoring the activities of key enzymes involved in the lignification process. There was a 40% reduction in lignin biosynthesis during wound healing in response to gamma irradiation. The level of the first enzyme involved in lignin biosyn...

The diversity of non-canonical amino acids (ncAAs) endows proteins with new features for a variety of biological studies and biotechnological applications. The genetic code expansion strategy, which co-translationally incorporates ncAAs into specific sites of target proteins, has been applied in many organisms. However, there have been only few studies on pathogens using genetic code expansion....

Lactic acid is readily utilized as a carbon and energy source by Neisseria gonorrhoeae. The oxidation of lactate is coupled to electron transport via a membrane-bound lactate dehydrogenase (iLDH) which is independent of pyridine nucleotide. The broad substrate specificity of iLDH endows N. gonorrhoeae with the novel ability to convert phenyllactate to L-phenylalanine via phenylpyruvate. N. gono...

We have investigated the basis for an increased level of proline dehydrogenase activity, the most prominent phenotype displayed by a mutant of Escherichia coli lacking leucyl-, phenylalanyl-tRNA:protein transferase. A dehydrogenase preparation of approximately 95% purity from the transferaseless mutant contained glycine, which is not an acceptor determinant in the transfer reaction, as the sole...

Copper-containing enzymes catalyze a broad spectrum of redox reactions. Thiocyanate dehydrogenase (TcDH) from Thioalkalivibrio paradoxus Arh1 enables the bacterium to use thiocyanate as unique source energy and nitrogen. Oxidation takes place in trinuclear copper center TcDH with peculiar organization. Despite crystal structure being established, role some residues enzyme active site has yet be...

Pretyrosine, an intermediate of L-tyrosine biosynthesis in blue-green algae, was found to be enzymatically formed and utilized in Pseudomonas aeruginosa. The enzymology and regulation of aromatic biosynthesis were re-evaluated in the context of these new findings, Four species of aromatic aminotranaferase were separated and partially purified. Each was reactive with prephenate, phenylpyruvate, ...