104-98-3Relevant articles and documents
Pseudomonas fluorescens Strain R124 Encodes Three Different MIO Enzymes
Csuka, Pál,Juhász, Vivien,Kohári, Szabolcs,Filip, Alina,Varga, Andrea,Sátorhelyi, Péter,Bencze, László Csaba,Barton, Hazel,Paizs, Csaba,Poppe, László
, p. 411 - 418 (2018)
A number of class I lyase-like enzymes, including aromatic ammonia-lyases and aromatic 2,3-aminomutases, contain the electrophilic 3,5-dihydro-5-methylidene-4H-imidazol-4-one (MIO) catalytic moiety. This study reveals that Pseudomonas fluorescens R124 strain isolated from a nutrient-limited cave encodes a histidine ammonia-lyase, a tyrosine/phenylalanine/histidine ammonia-lyase (XAL), and a phenylalanine 2,3-aminomutase (PAM), and demonstrates that an organism under nitrogen-limited conditions can develop novel nitrogen fixation and transformation pathways to enrich the possibility of nitrogen metabolism by gaining a PAM through horizontal gene transfer. The novel MIO enzymes are potential biocatalysts in the synthesis of enantiopure unnatural amino acids. The broad substrate acceptance and high thermal stability of PfXAL indicate that this enzyme is highly suitable for biocatalysis.
15N/14N position-specific isotopic analyses of polynitrogenous amino acids
Sacks, Gavin L.,Brenna, J. Thomas
, p. 1013 - 1019 (2005)
15N/14N isotope ratios are widely used to study processes and systems involving amino acids. Nitrogen isotope fractionation in biological processes occurs primarily at sites of bond-breaking and formation; the finest discrimination for "isotopic fingerprinting" and studies of isotopic fluxes is thus obtained at the position-specific level. While there are numerous reports of natural intramolecular carbon isotope variability, there are no literature reports of 15N/14N position-specific isotopic analysis (N-PSIA) of biologically relevant molecules. We report a methodology for high-precision N-PSIA of four polynitrogenous α-amino acids (asparagine, glutamine, lysine, histidine) and the first survey of natural intramolecular 15N/14N in these biomolecules. Selective liberation of N-atoms from multiple commercial standards of each parent amino acid was achieved by an appropriate enzymatic reaction or by acid hydrolysis. 15N/14N measurements were performed on N-ethoxycarbonyl ethyl ester derivatives of the parent amino acids and their analogues by gas chromatography combustion isotope ratio mass spectrometry, and the average precision for replicate injections was found to be SD(δ15N) = 0.3‰. Position-specific δ15N values of the parent amino acid were directly observed or indirectly calculated using mass balance. The average precision obtained for directly measured positions was SD(δ15N) = 0.2-0.4‰. The average precision for indirectly obtained positions was SD(δ15N) = 0.6-1.3‰ as a result of propagation of errors. Enrichment in the side chain-N with respect to the peptide-N was observed in nearly all of the amino acid sources, most notably in asparagine (average Δδside-peptide = +11‰), which may be indicative of its method of production. In some cases, it was possible to distinguish commercial sources by N-PSIA that could not be distinguished at the compound-specific level.
Sunscreen agents
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, (2008/06/13)
Hydroxy salts of formula: where M is zinc, copper or a mixture of the two and X denotes anions at least some of which display ultraviolet absorption over at least a portion of the wavelength range from 290 to 400 nanometers, their use as sunscreen agents and sunscreen compositions comprising them together with a cosmetically acceptable vehicle.
