Search results for "phenylalanine"
showing 10 items of 193 documents
Human milk enhances antioxidant defenses against hydroxyl radical aggression in preterm infants
2008
Background: Preterm infants endowed with an immature antioxidant defense system are prone to oxidative stress. Hydroxyl radicals are very aggressive reactive oxygen species that lack specific antioxidants. These radicals cannot be measured directly, but oxidation byproducts of DNA or phenylalanine in urine are reliable markers of their activity. Human milk has a higher antioxidant capacity than formula. Objective: We hypothesized that oxidative stress associated with prematurity could be diminished by feeding human milk. Design: We recruited a cohort of stable preterm infants who lacked perinatal conditions associated with oxidative stress; were not receiving prooxidant or antioxidant drugs…
Transmural distribution of biochemical markers of total protein and collagen synthesis, myocardial contraction speed and capillary density in the rat…
1988
The effect of angiotensin II-induced hypertension on selected biochemical parameters was studied in Sprague-Dawley rats. Angiotensin II infusion at rates of 41.7 micrograms h-1 kg-1 and 12.5 micrograms h-1 kg-1 for 2, 5, 10 and 15 days elevated the systolic blood pressure from 143 +/- 7 mmHg to 215-230 mmHg (P less than 0.001) and 185-195 mmHg (P less than 0.001), respectively. The left ventricular weight/body weight ratio increased 10-14% (P less than 0.05) and 23-32% (P less than 0.001) after 2-15 days in rats treated at the lower and higher infusion rates, respectively. Prolyl 4-hydroxylase (PH) activity, a marker of collagen synthesis, was evenly distributed in the left ventricle. PH ac…
Protein synthesis and cyclic GMP content in rat cardiac muscle after swimming exercise
1988
Rats were exercised for 6 h by swimming. Phenylalanine incorporation into myocardial proteins was increased when 2 h had elapsed after the termination of exercise. Cyclic GMP concentration did not change during the experiment, which indicates that cyclic GMP does not act directly as a trigger of myocardial protein synthesis in volume overload.
Redistribution of glucose uptake by chronic exercise, measured in isolated perfused rat hearts.
1985
The effects of 8-9 weeks of running and swimming training on the transmural distribution of cardiac glucose uptake and protein synthesis in isolated perfused heart were studied in male rats. The left ventricular glucose uptake in hearts from sedentary rats was 2.5 +/- 0.3 mumoles/min per g protein (mean +/- S.D.), and about 30% higher in the subendocardial layer than in the subepicardial layer (P less than 0.01). After the running and swimming programs the total left ventricular glucose uptake was at the level of sedentary rats, but the gradient was absent. The rate of protein synthesis was evenly distributed through the left ventricular wall and similar in all experimental groups. The alte…
Regional glucose uptake and protein synthesis in isolated perfused rat hearts immediately after training and later
1987
The effect of 10 weeks of running training and termination of training on the regional distribution of cardiac glucose uptake and protein synthesis were studied in isolated perfused hearts in male rats. The left ventricular glucose uptake in hearts from sedentary rats was 1.87 +/- 0.14 mumol/min per g protein (mean +/- SE), being about 30% higher in the subendocardial than in the subepicardial layer (p less than 0.05). The gradient of left ventricular glucose uptake was similar to the controls in the rats retired from training, but was absent in the trained animals. The altered transmural glucose uptake probably reflects differences in the adaptive response of various myocardial muscle laye…
Phenguignardic acid and guignardic acid, phytotoxic secondary metabolites from Guignardia bidwellii.
2012
Bioactivity-guided isolation led to the identification of phenguignardic acid (2), a new phytotoxic secondary metabolite from submerged cultures of grape black rot fungus, Guignardia bidwellii. The compound is structurally related to guignardic acid (1), a dioxolanone moiety-containing metabolite isolated previously from Guignardia species. However, in contrast to guignardic acid, which is presumably synthesized from deamination products of valine and phenylalanine, the biochemical precursor for the biosynthesis of the new phytotoxin appears to be exclusively phenylalanine. Guignardic acid was also found in extracts of cultures from Guignardia bidwellii. The phytotoxic activities of both co…
Effects of side-chain orientation on the backbone conformation of the dehydrophenylalanine residue. Theoretical and X-ray study.
2011
Two E isomers of α,β-dehydro-phenylalanine, Ac-(E)-ΔPhe-NHMe (1a) and Ac-(E)-ΔPhe-NMe(2) (2a), have been synthesized and their low temperature structures determined by single-crystal X-ray diffraction. A systematic theoretical analysis was performed on these molecules and their Z isomers (1b and 2b). The ϕ,ψ potential energy surfaces were calculated at the MP2/6-31+G(d,p) and B3LYP/6-31+G(d,p) levels in the gas phase and at the B3LYP/6-31+G(d,p) level in the chloroform and water solutions with the SCRF-PCM method. All minima were fully optimized by the MP2 and DFT methods, and their relative stabilities were analyzed in terms of π-conjugation, internal H-bonds, and dipole-dipole interaction…
Site-by-site tracking of signal transduction in an azidophenylalanine-labeled bacteriophytochrome with step-scan FTIR spectroscopy
2021
Signal propagation in photosensory proteins is a complex and multidimensional event. Unraveling such mechanisms site-specifically in real time is an eligible but a challenging goal. Here, we elucidate the site-specific events in a red-light sensing phytochrome using the unnatural amino acid azidophenylalanine, vibrationally distinguishable from all other protein signals. In canonical phytochromes, signal transduction starts with isomerization of an excited bilin chromophore, initiating a multitude of processes in the photosensory unit of the protein, which eventually control the biochemical activity of the output domain, nanometers away from the chromophore. By implementing the label in pri…
Density functional study of Cu2+-phenylalanine complex under micro-solvation environment
2013
Abstract We present an atomistic study carried out using density functional calculations including structural relaxations and Car–Parrinello Molecular Dynamics (CPMD) simulations, aiming to investigate the structures of phenylalanine-copper (II) ([Phe-Cu] 2+ ) complexes and their micro-solvation processes. The structures of the [Phe-Cu] 2+ complex with up to four water molecules are optimized using the B3LYP/6-311++G** model in gas phase to identify the lowest energy structures at each degree of solvation ( n = 0–4). It is found that the phenylalanine appears to be in the neutral form in isolated and mono-hydrated complexes, but in the zwitterionic form in other hydrated complexes (with n …
Size- and Structure-Selective Noncovalent Recognition of Saccharides by Tetraethyl and Tetraphenyl Resorcinarenes in the Gas Phase
2008
The noncovalent complexation of tetraethyl and tetraphenyl resorcinarenes with mono-, di-, and oligosaccharides was studied with negative-polarization electrospray ionization quadrupole ion trap and electrospray ionization Fourier-transform ion cyclotron resonance mass-spectrometric analysis. The saccharides formed 1:1 complexes with deprotonated resorcinarenes, which exhibited clear size and structure selectivity in their complexation. In the case of the monosaccharides, hexoses formed much more abundant and kinetically stable complexes than pentoses or deoxyhexoses. A comparison of the mono-, di-, and oligosaccharides revealed that both the relative abundance and stability of the complexe…