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Enzymatic reductive amination of p-hydroxy- and phenylpyruvic acids as a method of synthesis of L-tyrosine and L-phenylalanine labelled with deuterium and tritium

Pałka K., Kańska M.

Nukleonika

2012

Vol. 57, No. 3

383-387

We report the synthesis of isotopomers of L-phenylalanine and L-tyrosine selectively labelled with hydrogen isotopes in the 2-position of the side chain. The deuterium or tritium label was introduced using reductive amination activity of enzyme L-phenylalanine dehydrogenase (EC 1.4.1.20). This way p-phenylpyruvic acid was converted into [2-2H]-, [2-3H]-, and doubly labelled [2-2H/3H]-isotopomers of L-phenylalanine, using deuteriated, tritiated, and mixed (DTO) incubation media, respectively. Similarly, p-hydroxyphenylpyruvic acid was converted into [2-2H]-, [2-3H]-, and [2-2H/3H]-L-tyrosine. Deuterium labelled isotopomers of L-phenylalanine and --tyrosine can be used as markers in the investigation of abnormal metabolism of these amino acids observed in patients with inborn genetic diseases such as phenylketonuria and tyrosinemia.

Usefulness of spectroscopy for biomedical engineering

Olsztyńska-Janus S., Szymborska K., Komorowska M., Lipiński J.

Acta of Bioengineering and Biomechanics

2008

Vol. 10, nr 3

45-49

Modifications of phenylalanine amino acid after its exposure to near-infrared (NIR) radiation have been investigated using ATRFTIR (Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy). The process of amino acid aggregation after its exposure to NIR has been observed. A possible mechanism of amino acid dimer formation has been proposed with the help of theoretical calculations of quantum mechanics (MP2 and B3LYP/6–31 G* level) using the GAUSSIAN 03 package. The usefulness of spectroscopy for biomedical engineering is discussed. ATR-FTIR appears to be a powerful tool for measuring tissue damage in aqueous environments.

Kinetics and mechanism of oxidation of L-phenylalanine by alkaline permanganate

Panari R.G., Chougale R.B., Nandibewoor S.T.

Polish Journal of Chemistry

1998

Vol. 72, nr 1

99-107

The data suggest that the oxidation of L-phenylalanine proceeds via the formation of a complex between L-phenylalanine and permanganate which decomposes slowly, followed by a fast reaction between the free radical of L-phenylalanine and another molecule of permanganate to give the products. The reaction constants involved in the mechanism are derived. There is a good agreement between the observed and calculated rate contants at varying conditions of experiments. The activation parameters are computed with respect to the slow step of the mechanism.