L-Phenylalanine

The seeds of Glycine max (L.) Merr

H-Phe-OH

A study of the antibacterial activity of L-phenylalanine and L-tyrosine esters in relation to their CMCs and their interactions with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine, DPPC as model membrane.[Pubmed:24667307]

Microbiol Res. 2014 Sep-Oct;169(9-10):675-85.

Cationic amino acid-based surfactants are known to interact with the lipid bilayer of cell membranes resulting in depolarization, lysis and cell death through a disruption of the membrane topology. A range of cationic surfactant analogues derived from L-Phenylalanine (C1-C20) and L-Tyrosine (C8-C14) esters have been synthesized and screened for their antibacterial activity. The esters were more active against gram positive than gram negative bacteria. The activity increased with increasing chain length, exhibiting a cut-off effect at C12 for gram positive and C8/C10 for gram negative bacteria. The cut-off effect for gram negative bacteria was observed at a lower alkyl chain length. The CMC was correlated with the MIC, inferring that micellar activity contribute to the cut-off effect in antibacterial activity. The interaction of the cationic surfactants with the phospholipid vesicles (1,2-dipalmitoyl-sn-glycero-3-phosphocholine, DPPC) in the presence of 1-anilino-8-naphthalene sulfonate (ANS) and 1,6-diphenyl-1,3,5-hexatriene (DPH) as fluorescence probes showed that an increase in ionic interaction causes an increase in antibacterial activity. Increase in hydrophobic interaction increases the antibacterial activity only to a certain chain length, attributing to the cut-off effect. Therefore, both electrostatic and hydrophobic interactions, involving the polar and nonpolar moieties are of paramount importance for the bactericidal properties.

Improvement of constraint-based flux estimation during L-phenylalanine production with Escherichia coli using targeted knock-out mutants.[Pubmed:24449451]

Biotechnol Bioeng. 2014 Jul;111(7):1406-16.

Fed-batch production of the aromatic amino acid L-Phenylalanine was studied with recombinant Escherichia coli strains on a 15 L-scale using glycerol as carbon source. Flux Variability Analysis (FVA) was applied for intracellular flux estimation to obtain an insight into intracellular flux distribution during L-Phenylalanine production. Variability analysis revealed great flux uncertainties in the central carbon metabolism, especially concerning malate consumption. Due to these results two recombinant strains were genetically engineered differing in the ability of malate degradation and anaplerotic reactions (E. coli FUS4.11 DeltamaeA pF81kan and E. coli FUS4.11 DeltamaeA DeltamaeB pF81kan). Applying these malic enzyme knock-out mutants in the standardized L-Phenylalanine production process resulted in almost identical process performances (e.g., L-Phenylalanine concentration, production rate and byproduct formation). This clearly highlighted great redundancies in central metabolism in E. coli. Uncertainties of intracellular flux estimations by constraint-based analyses during fed-batch production of L-Phenylalanine were drastically reduced by application of the malic enzyme knock-out mutants.

[Microbial synthesis of deuterium labelled L-phenylalanine with different levels of isotopic enrichment by facultative methylotrophic bacterium Brevibacterium methylicum with RMP assimilation of carbon].[Pubmed:25249528]

Biomed Khim. 2014 Jul-Aug;60(4):448-61.

The preparative microbial synthesis of amino acids labelled with stable isotopes, including deuterium ( 2 H), suitable for biomedical applications by methylotrophic bacteria was studied using L-Phenylalanine as example. This amino acid is secreted by Gram-negative aerobic facultative methylotrophic bacteria Brevibacterium methylicum, assimilating methanol via ribulose-5-monophosphate (RMP) cycle of assimilation of carbon, The data on adaptation of L-Phenylalanine secreted by methylotrophic bacterium capital VE, Cyrillic. methylicum to the maximal concentration of deuterium in the growth medium with 98% 2 capital EN, Cyrillic 2 O and 2% [ 2 capital EN, Cyrillic]methanol, and biosynthesis of deuterium labelled L-Phenylalanine With different levels of enrichment are presented. The strain was adapted by means of plating initial cells on firm (2% agarose) minimal growth media with an increasing gradient of 2 capital EN, Cyrillic 2 O concentration from 0; 24.5; 49.0; 73.5 up to 98% 2 capital EN, Cyrillic 2 O followed by subsequent selection of separate colonies stable to the action of 2 capital EN, Cyrillic 2 O. These colonies were capable to produce L-Phenylalanine. L-Phenylalanine was extracted from growth medium by extraction with isopropanol with the subsequent crystallization in ethanol (output 0.65 g/l). The developed method of microbial synthesis allows to obtain deuterium labelled L-Phenylalanine with different levels of isotopic enrichment, depending on concentration of 2 capital EN, Cyrillic 2 O in growth media, from 17% (on growth medium with 24,5% 2 capital EN, Cyrillic 2 O) up to 75% (on growth medium with 98% 2 capital EN, Cyrillic 2 O) of deuterium in the molecule that is confirmed with the data of the electron impact (EI) mass- spectrometry analysis of methyl ethers of N-dimethylamino(naphthalene)-5-sulfochloride (dansyl) phenylalanine in these experimental conditions.

L-Phenylalanine ((S)-2-Amino-3-phenylpropionic acid) is an essential amino acid isolated from Escherichia coli. L-Phenylalanine is a α2δ subunit of voltage-dependent Ca+ channels antagonist with a Ki of 980 nM. L-phenylalanine is a competitive antagonist for the glycine- and glutamate-binding sites of N-methyl-D-aspartate receptors (NMDARs) (KB of 573 μM ) and non-NMDARs, respectively. L-Phenylalanine is widely used in the production of food flavors and pharmaceuticals.

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