In an effort to establish reliable thermodynamic data for proteinogenic amino acids, heat capacities for l-histidine (CAS RN: 71-00-1), l-phenylalanine (CAS RN: 63-91-2), l-proline (CAS RN: 147-85-3), l-tryptophan (CAS RN: 73-22-3), and l-tyrosine (CAS RN: 60-18-4) were measured over a wide temperature range. Prior to heat capacity measurements, thermogravimetric analysis was performed to determine the decomposition temperatures while X-ray powder diffraction (XRPD) and heat-flux differential scanning calorimetry (DSC) were used to identify the initial crystal structures and their possible transformations. Crystal heat capacities of all five amino acids were measured by Tian-Calvet calorimetry in the temperature interval from 262 to 358 K and by power compensation DSC in the temperature interval from 307 to 437 K. Experimental values determined in this work were then combined with the literature data obtained by adiabatic calorimetry. Low temperature heat capacities of l-histidine, for which no literature data were available, were determined in this work using the relaxation (heat pulse) calorimetry from 2 K. As a result, isobaric crystal heat capacities and standard thermodynamic functions up to 430 K for all five crystalline amino acids were developed.

• Klíčová slova
• crystal heat capacity, l-histidine, l-phenylalanine, l-proline, l-tryptophan, l-tyrosine, thermodynamic functions,
• MeSH
• fenylalanin chemie   MeSH
• histidin chemie   MeSH
• prolin chemie   MeSH
• termodynamika MeSH
• tryptofan chemie   MeSH
• tyrosin chemie   MeSH
• vysoká teplota MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• fenylalanin MeSH
• histidin MeSH
• prolin MeSH
• tryptofan MeSH
• tyrosin MeSH

A number of tryptophan-plus-tyrosine double auxotrophs have been isolated from a glutamate producing Arthrobacter globiformis excreting L-phenylalanine by two-step mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine. For the three potent mutants tested the medium of Alföldi was found to be the best. The optimum tryptophan, tyrosine and biotin concentrations for phenylalanine production of these mutants were 0.5 mmol/L, 0.1 mmol/L and 5 micrograms/L, respectively. At these levels strain TT-39 yielded 2.6 g phenylalanine per L of medium in flask culture with glucose (350 mmol/L) and NH4Cl (60 mmol/L).

• MeSH
• Arthrobacter genetika   růst a vývoj   metabolismus   MeSH
• biotin farmakologie   MeSH
• fenylalanin biosyntéza   účinky léků   MeSH
• kultivační média farmakologie   MeSH
• methylnitronitrosoguanidin farmakologie   MeSH
• mutageneze * MeSH
• tryptofan farmakologie   MeSH
• tyrosin farmakologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• biotin MeSH
• fenylalanin MeSH
• kultivační média MeSH
• methylnitronitrosoguanidin MeSH
• tryptofan MeSH
• tyrosin MeSH

The interaction of L-phenylalanine with a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) monolayer at the air-water interface was explored using a combination of experimental techniques and molecular dynamics (MD) simulations. By means of Langmuir trough methods and Brewster angle microscopy, L-phenylalanine was shown to significantly alter the interfacial tension and the surface domain morphology of the DPPC film. In addition, confocal microscopy was used to explore the aggregation state of L-phenylalanine in the bulk aqueous phase. Finally, MD simulations were performed to gain molecular-level information on the interactions of L-phenylalanine and DPPC at the interface. Taken together, these results show that L-phenylalanine intercalates into a DPPC film at the air-water interface, thereby affecting the surface tension, phase morphology, and ordering of the DPPC film. The results are discussed in the context of biological systems and the mechanism of diseases such as phenylketonuria.

• MeSH
• 1,2-dipalmitoylfosfatidylcholin analogy a deriváty   chemie   MeSH
• deuterium chemie   MeSH
• fenylalanin chemie   MeSH
• mikroskopie MeSH
• molekulární struktura MeSH
• povrchové vlastnosti MeSH
• simulace molekulární dynamiky MeSH
• voda chemie   MeSH
• vzduch * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH
• Názvy látek
• 1,2-dipalmitoylfosfatidylcholin MeSH
• colfosceril palmitate MeSH Prohlížeč
• deuterium MeSH
• fenylalanin MeSH
• voda MeSH

• MeSH
• aspartam analýza   MeSH
• dipeptidy analýza   MeSH
• fluorescenční spektrometrie metody   MeSH
• tablety MeSH
• Publikační typ
• anglický abstrakt MeSH
• časopisecké články MeSH
• Názvy látek
• aspartam MeSH
• dipeptidy MeSH
• tablety MeSH

Phenylalanine ammonia-lyase (PAL) activity, contents of phenolic acids and ethylene production during the lag-phase, and contents of phenolic acids at the late exponential phase, showed significant differences in embryogenic (EC) and non-embryogenic (NEC) suspension cultures of Medicago sativa L. Maximum PAL activity at 6 h after inoculation was followed by an increase in the level of phenolic acids from 9.6 μg g(-1) fresh mass to 21 μg g(-1) fresh mass in NEC at 12 h. Thereafter the level of phenolic acids decreased to 5.2 μg g(-1) fresh mass at 72 h. The decline was caused predominantly by the decrease of ester-bound cinnamic acid derivatives, the decrease ranging from 83 to 20% of total phenolics. Two maxima of ethylene production were observed in NEC: the first one immediately after inoculation and the second at 6 h, coinciding with the peak of PAL activity. In NEC, most of the phenolic acids occurred in esterified form. Ability to form somatic embryos (EC) was associated with the absence of the second peak of ethylene production as well as of the peak of PAL activity at 6 h. The level of phenolic acids during the lag-phase remained low (7.2 μg g(-1) FM) and did not change. The proportion of cinnamic acid derivatives was very low (18% of total phenolics), mostly due to the extremely low level of ferulic acid. In EC, phenolic acids bound to methanol insoluble material formed the major fraction. Loss of embryogenic potential of the embryogenic culture (ECL) was associated with qualitative and quantitative changes in the contents of phenolic acids insignificantly increased PAL activity after inoculation was followed by a moderate increase in the contents of phenolic acids from 9.35 μg g(-1) fresh mass to 12.42 μg g fresh mass. A high rate of ethylene production was observed only immediately after the transfer of the culture to fresh medium. The loss of embryogenicity correlated also with changes in the relative amounts of the investigated fractions of phenolic acids. A distinct increase in the level of methoxy-substituted phenolic acids is a characteristic feature of the ECL culture.

• Publikační typ
• časopisecké články MeSH

The effect of potential precursors (cinnamic acid, phenylalanine, tyrosine) in three concentrations (0.01; 0.1; 1 mmol/l) on the growth of the culture and coumarin production was investigated in the suspension culture of Angelica archangelica L. The cultures were cultivated under constant illumination (3500 lux) and in the dark. The growth of the culture in the dark was not affected by the precursors, cinnamic acid in a concentration of 1 mmol/l exerted toxic action. The growth of the culture cultivated under constant illumination was stimulated by tyrosine in a concentration of 0.1 and 1 mmol/l, and phenylalanine in a concentration of 0.1 mmol/l; phenylalanine and cinnamic acid in a concentration of 1 mmol/l inhibited the growth of the culture. In the cultivation in the dark, coumarin production was increased by phenylalanine in a concentration 0.01 mmol/l and by tyrosine in a concentration of 1 mmol/l. In the cultivation under constant illumination, coumarin production was decreased by the action of cinnamic acid, was not affected by tyrosine, and phenylalanine (0.01 and 0.1 mmol/l) increased it in comparison with the culture without precursors.

• MeSH
• Angelica archangelica metabolismus   MeSH
• cinnamáty farmakologie   MeSH
• fenylalanin farmakologie   MeSH
• kultivační techniky MeSH
• kumariny metabolismus   MeSH
• léčivé rostliny metabolismus   MeSH
• tyrosin farmakologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• cinnamáty MeSH
• cinnamic acid MeSH Prohlížeč
• fenylalanin MeSH
• kumariny MeSH
• tyrosin MeSH

The EEG of 10 phenylketonuric children treated by a diet and of 4 children with hyperphenylalaninaemia on a normal diet was recorded during L-phenylalanine tolerance tests. The first recording was made before administering the L-phenylalanine load (100 mg/kg b.w.) and the second 60-120 min after. In 6 of the phenylketonuric children, nonspecific abnormality became more pronounced or increased, or previously absent epileptic graphoelements appeared. A pathological EEG response to a L-phenylalanine load was found in 1 child with hyperphenylalaninaemia. The authors do not recommend relaxation of the diet in children with a pathological EEG response to a L-phenylalanine load.

• MeSH
• diferenciální diagnóza MeSH
• dítě MeSH
• dospělí MeSH
• elektroencefalografie MeSH
• fenylalanin * MeSH
• fenylketonurie diagnóza   genetika   MeSH
• heterozygot MeSH
• lidé MeSH
• Check Tag
• dítě MeSH
• dospělí MeSH
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• srovnávací studie MeSH
• Názvy látek
• fenylalanin * MeSH

The determination of phenylalanine and tyrosine is presently the most reliable direct approach to the diagnosis of phenylketonuria. An HPLC method for the simultaneous measurement of phenylalanine and tyrosine in samples of dried blood spots and plasma has been developed and evaluated. We have used an inherent fluorescence of both phenylalanine and tyrosine. For the separation, a reverse-phase column LiChroCart 125-4, Purospher RP-18e, 5microm, was used. The mixture of ethanol and deionized water (5:95, v/v) was used as a mobile phase. Analytical performance of this method is satisfactory for both phenylalanine and tyrosine: the intra-assay and inter-assay coefficients of variation were below 10%. Quantitative recoveries from spiked plasma and blood samples were between 92.0 and 102.9%. The limit of detection was 10.0 and 5.0micromol/L, respectively. The preliminary reference ranges of phenylalanine and tyrosine in a group of newborns are 69.3+/-13.1 and 42.7+/-12.9micromol/L, in a group of blood donors are 68.4+/-9.9 and 52.1+/-10.9micromol/L. The presented method is inexpensive and suitable for diagnosis of phenylketonuria.

• MeSH
• dospělí MeSH
• fenylalanin krev   MeSH
• fluorescence MeSH
• lidé středního věku MeSH
• lidé MeSH
• tyrosin krev   MeSH
• vysokoúčinná kapalinová chromatografie přístrojové vybavení   metody   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• hodnotící studie MeSH
• práce podpořená grantem MeSH
• Názvy látek
• fenylalanin MeSH
• tyrosin MeSH

Monitoring patients with phenylketonuria (PKU) requires accurately measuring phenylalanine and tyrosine levels in a small volume of blood samples obtained by the dried blood spot (DBS) technique. The aim was to study selected parameters influencing the quantitative results. Phenylalanine and tyrosine were extracted from DBS samples with methanol, and 5 internal standard introduction techniques were tested. Phenylalanine and tyrosine levels were measured in 6-mm discs punched from DBS, pre-punched 9-mm discs containing the entire DBS sample, and liquid blood by HPLC-MS-MS. Levels in 6-mm discs punched from DBS measured by HPLC-MS/MS were compared with those measured by the HPLC-FLD. The analytical parameters of the method are satisfactory, linearity in the range of 25-1200 μmol/L (LOD, LOQ and LLOQ values 0.2 μmol/L, 0.5 μmol/L and 3.8 μmol/L for phenylalanine, 0.5 μmol/L, 1.5 μmol/L and 5.1 μmol/L for tyrosine), within-run precision 1.8 %-3.7 % for phenylalanine, 1.9 %-2.7 % for tyrosine, between-run precision 4.7 %-5.9 % for phenylalanine, 4.1 %-5.4 % for tyrosine, recovery 93.8 %-100.4 % for phenylalanine and 93.7 %-99.1 % for tyrosine. Good agreement was found between phenylalanine and tyrosine concentrations in 6-mm discs punched from DBS (R = 0.896, p < 0.001, and R = 0.907, p < 0.001, respectively), pre-punched 9-mm discs containing the entire DBS sample (R = 0.960, p < 0.001, and R = 0.950, p < 0.001, respectively) and liquid blood, as well as between phenylalanine and tyrosine concentrations obtained by HPLC-MS/MS and HPLC-FLD (R = 0.968, p < 0.001, and R = 0.984, p < 0.001, respectively). The presented method is suitable for monitoring patients with PKU.

• Klíčová slova
• Dried blood spot, Liquid chromatography with mass spectrometry and fluorescence detection, Parameters affecting quantitative results, Phenylalanine, Tyrosine,
• MeSH
• fenylalanin * krev   MeSH
• fenylketonurie * krev   diagnóza   MeSH
• lidé MeSH
• limita detekce MeSH
• reprodukovatelnost výsledků MeSH
• tandemová hmotnostní spektrometrie metody   MeSH
• test suché kapky krve * metody   MeSH
• tyrosin * krev   MeSH
• vysokoúčinná kapalinová chromatografie metody   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• fenylalanin * MeSH
• tyrosin * MeSH

• MeSH
• alanintransaminasa metabolismus   MeSH
• fenylalanin farmakologie   MeSH
• glukoneogeneze účinky léků   MeSH
• játra enzymologie   MeSH
• kyseliny fenylpyrohroznové farmakologie   MeSH
• L-laktátdehydrogenasa metabolismus   MeSH
• lidé MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• anglický abstrakt MeSH
• časopisecké články MeSH
• Názvy látek
• alanintransaminasa MeSH
• fenylalanin MeSH
• kyseliny fenylpyrohroznové MeSH
• L-laktátdehydrogenasa MeSH