scholarly journals Structural factors influencing the reaction rates of 4-aryloxy-7-nitrobenzofurazans with amino acids

2004 ◽  
Vol 2 (4) ◽  
pp. 672-685 ◽  
Author(s):  
Marioara Bem ◽  
Marilena Vasilescu ◽  
Miron Caproiu ◽  
Constantin Draghici ◽  
Adrian Beteringhe ◽  
...  
Keyword(s):  
Amino Acids ◽  
Room Temperature ◽  
Reaction Rates ◽  
Structural Factors ◽  
Basic Amino Acids ◽  
Interesting Observation ◽  
Neutral Amino Acids ◽  
Acidic Amino Acids ◽  
Factors Influencing ◽  
Snar Reaction

AbstractAn interesting observation was made when studying the SNAr reaction between several 4-aryloxy-7-nitrobenzofurazans (2) and several amino acids leading to the apparition of detectable fluorescence from the substitution products3. Acidic amino acids reacted very slowly=while basic amino acids react fastest with2 having an unsubstituted phenyl or a 4-formyl-phenyl Ar group. Amongst neutral amino acids, proline reacts fastest at room temperature after 100 min. With2 having a methoxy-subtituted Ar group.

Atypical amino acids inhibit histidine, valine, or lysine transport into rat brain

1983 ◽  
Vol 245 (4) ◽  
pp. R556-R563 ◽  
Author(s):  
J. K. Tews ◽  
A. E. Harper
Keyword(s):  
Amino Acids ◽  
Rat Brain ◽  
Blood Brain Barrier ◽  
Brain Slices ◽  
Aromatic Amino Acids ◽  
Brain Barrier ◽  
Basic Amino Acids ◽  
Large Neutral Amino Acids ◽  
Neutral Amino Acids ◽  
Single Meal

Transport of histidine, valine, or lysine into rat brain slices and across the blood-brain barrier (BBB) was determined in the presence of atypical nonprotein amino acids. Competitors of histidine and valine transport in slices were large neutral amino acids including norleucine, norvaline, alpha-aminooctanoate, beta-methylphenylalanine, and alpha-aminophenylacetate. Less effective were aromatic amino acids with ring substituents; ineffective were basic amino acids and omega-amino isomers of norleucine and aminooctanoate. Lysine transport was moderately depressed by homoarginine or ornithine plus arginine; large neutral amino acids were also similarly inhibitory. Histidine or valine transport across the BBB was also strongly inhibited by large neutral amino acids that were the most effective competitors in the slices (norvaline, norleucine, alpha-aminooctanoate, and alpha-aminophenylacetate); homoarginine and 8-aminooctanoate were ineffective. Homoarginine, ornithine, and arginine almost completely blocked lysine transport, but the large neutral amino acids were barely inhibitory. When rats were fed a single meal containing individual atypical large neutral amino acids or homoarginine, brain pools of certain large neutral amino acids or of arginine and lysine, respectively, were depleted.

Rapid Single Column Analysis of Amino Acids Related to Some Aminoacidopathies

1969 ◽  
Vol 15 (7) ◽  
pp. 621-630 ◽  
Author(s):  
James V Benson ◽  
Jean Cormick ◽  
James A Patterson
Keyword(s):  
Amino Acids ◽  
Human Serum ◽  
Sodium Citrate ◽  
Step Change ◽  
Complete Analysis ◽  
Basic Amino Acids ◽  
Neutral Amino Acids ◽  
Single Column ◽  
Column Procedure ◽  
Change System

Abstract A single-column procedure, using Type UR-30 resin to develop acidic, neutral, and basic amino acids normally found in protein or peptide hydrolyzates is reported for the study, in human serum, of amino acids associated with some aminoacidopathies. Using a sodium citrate, three-buffer, step-change system, pH 3.28 (0.20 N), pH 4.30 (0.20 N), and pH 6.71 (1.0 N), the acidic and neutral amino acids are chromato-graphed in 85 min. A complete analysis including the basic amino acids requires 135 min. This resin also will perform the function of earlier resins—ie, the separation of the acidic and neutral amino acids by the simple hydrolyzate procedures and by the more complex physiologic procedures.

Interactions of neutral and acidic amino acids in renal tubular transport

1962 ◽  
Vol 202 (3) ◽  
pp. 577-583 ◽  
Author(s):  
William A. Webber
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Plasma Concentrations ◽  
Side Chain ◽  
Neutral Amino Acids ◽  
Acidic Amino Acids ◽  
Renal Tubular Reabsorption ◽  
Renal Tubular Transport ◽  
Renal Tubular ◽  
Amino Acid Concentrations

The effects of intravenous infusions of a variety of neutral and acidic amino acids on the plasma concentrations and excretions of naturally occurring amino acids were studied in dogs. Conventional clearance techniques were used, and the amino acid concentrations were determined by ion exchange column chromatography. Infusion of either l-glutamic acid or l-aspartic acid caused a gross increase in the plasma concentration and excretion of the other. Infusions of neutral amino acids including glycine, l-alanine, l-leucine, l-methionine, l-proline, and l-phenylalanine caused some minor changes in the endogenous plasma amino acid concentrations. They produced increases in the excretion of other neutral amino acids and, in some cases, of acidic and basic amino acids as well. In general, amino acids with long side chains were most effective in inhibiting reabsorption while cyclic side-chain compounds were less effective. There appear to be at least three somewhat separable mechanisms for renal tubular reabsorption of amino acids in dogs.

Intercalation of basic amino acids into layered zirconium proline-N-methylphosphonate phosphate

2011 ◽  
Vol 65 (5) ◽  
Author(s):  
Ren-Quan Zeng ◽  
Xiang-Kai Fu ◽  
Xin-Bin Yang
Keyword(s):  
Amino Acids ◽  
Inductively Coupled Plasma ◽  
Room Temperature ◽  
Plasma Analysis ◽  
X Ray ◽  
Basic Amino Acids ◽  
Inductively Coupled ◽  
Ft Ir ◽  
Xrd Patterns ◽  
Ir And Raman

AbstractIntercalation of basic amino acids into layered zirconium proline-N-methylphosphonate phosphate (α-ZPMP) was investigated at room temperature. Three kinds of host-guest compounds were prepared and characterised by elemental analysis, inductively coupled plasma analysis (ICP), Fourier transform infrared spectrum (FT-IR), Raman spectrum, X-ray powder diffraction (XRD) and thermoanalysis. The interaction of amino acid guests with P-OH of α-ZPMP host was documented by FT-IR and Raman spectra. In addition, the XRD patterns indicated that l-arginine or l-lysine were intercalated into the interlayer galleries of α-ZPMP host; the interlayer distances of the Larginine and l-lysine intercalation compounds were expanded from 1.520 nm to 2.218 nm and 2.207 nm, respectively. l-arginine and l-lysine would be arranged as a mono-molecule layer in different orientations. The interlayer distance of l-histidine (d = 1.522 nm) was similar to that of α-ZPMP host (d = 1.520 nm), l-histidine might be adsorbed on the outer surface of the α-ZPMP host. Thermoanalysis showed that the intercalated l-arginine and l-lysine were removed at 110–305°C or 150–250°C, respectively, the adsorbed l-histidine was released at a temperature of up to 320°C.

N-Methylamino acids in peptide synthesis. V. The synthesis of N-tert-butyloxycarbonyl, N-methylamino acids by N-methylation

1977 ◽  
Vol 55 (5) ◽  
pp. 906-910 ◽  
Author(s):  
S. T. Cheung ◽  
N. Leo Benoiton
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Methyl Iodide ◽  
Peptide Synthesis ◽  
Room Temperature ◽  
Sodium Hydride ◽  
Amino Acid Derivatives ◽  
Enantiomerically Pure ◽  
Neutral Amino Acids ◽  
Related Data

The preparation of enantiomerically pure N-tert-butyloxycarbonyl,N-methylamino acids by N-methylation of the parent amino acid derivatives using sodium hydride and methyl iodide in tetrahydrofuran at room temperature is described for neutral amino acids including O-benzyl-protected threonine and tyrosine. Methylation of the O-benzylserine derivative under these conditions gives the N-methyldehydroalanine derivative. The β-elimination is completely suppressed, giving the corresponding N-methylserine derivative when the reaction is carried out at 5 °C. Other related data on N-methylation and N-methylamino acid derivatives are presented.

Effect of amino acids on choline uptake and phosphatidylcholine biosynthesis in the isolated hamster heart

1988 ◽  
Vol 66 (5) ◽  
pp. 418-424 ◽  
Author(s):  
Grant M. Hatch ◽  
Willem K. Stevens ◽  
Patrick C. Choy
Keyword(s):  
Amino Acids ◽  
Direct Interaction ◽  
Choline Uptake ◽  
Choline Transport ◽  
Neutral Amino Acids ◽  
Acidic Amino Acids ◽  
Phosphatidylcholine Biosynthesis ◽  
Concentration Threshold ◽  
Hamster Heart ◽  
Dose Dependent

Choline uptake by the hamster heart has been shown to be enhanced by exogenous glycine. In this study, the effect of neutral, basic, and acidic amino acids on choline uptake was assessed. Hamster hearts were perfused with labelled choline, and in the presence of L-alanine, L-serine, or L-phenylalanine (≥0.1 mM), choline uptake was enhanced 20–38%. L-Arginine, L-lysine, L-aspartate, and L-glutamate did not influence choline uptake. The rate of phosphatidylcholine biosynthesis was unaffected by all amino acids tested. Enhancement of choline uptake by neutral amino acids was not additive or dose dependent but required a concentration threshold. The enhancement of choline uptake by neutral amino acids was not influenced by preperfusion with the same amino acid. Exogenous choline had no effect on the uptake of amino acids. We postulate that choline and the neutral amino acids are not cotransported and modulation of choline uptake is facilitated by direct interaction of the neutral amino acids with the choline transport system.

Basic amino acid transport in renal papilla: microinfusion of Henle's loops and vasa recta

1993 ◽  
Vol 265 (6) ◽  
pp. F830-F838 ◽  
Author(s):  
W. H. Dantzler ◽  
S. Silbernagl
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Transport ◽  
Basic Amino Acid ◽  
Renal Papilla ◽  
Tubular Structures ◽  
Acid Transport ◽  
Basic Amino Acids ◽  
Neutral Amino Acids ◽  
Vasa Recta

To determine whether basic amino acids, like acidic and neutral amino acids, could be reabsorbed distal to tips of Henle's loops and recycled between loops and vasa recta in the renal papilla, we continuously microinfused ascending Henle's loops and vasa recta with 14C-labeled L-lysine (L-Lys; 1.28 mM) or L-arginine (L-Arg; 1.17 mM) and 3H-labeled inulin. We also determined percent of recovered radiolabel as intact amino acid. Like acidic and neutral amino acids, relative to inulin, approximately 30% of L-Lys and approximately 45% of L-Arg microinfused into Henle's loops were reabsorbed. However, whereas radiolabeled L-Lys reabsorption, like reabsorption of acidic and neutral amino acids, was not readily inhibited, radiolabeled L-Arg reabsorption was reduced to approximately 25% by addition of unlabled L-Arg (50 mM) or L-homoarginine (L-Homo-Arg) (50 mM) to infusate. This observation provides greater evidence for specific, carrier-mediated reabsorption for L-Arg than for acidic or neutral amino acids. About 36% (relative to inulin) of each of these amino acids microinfused into ascending vasa recta apparently was transferred directly into ipsilateral tubular structures (probably thin descending limbs of Henle's loops). Transfer of radiolabeled L-Arg was reduced to approximately 8% by the inclusion of unlabeled L-Arg (50 mM) in infusate. Transfer of unlabeled L-Lys was unaffected by inclusion of unlabeled L-Lys (50 mM) in infusate but was reduced to approximately 20% by inclusion of unlabeled L-Arg (50 mM) or L-Homo-Arg (50 mM) in infusate. (ABSTRACT TRUNCATED AT 250 WORDS)

High sensitivity of Xenopus gustatory receptors to amino acids and bitter substances

1982 ◽  
Vol 243 (1) ◽  
pp. R42-R48 ◽  
Author(s):  
K. Yoshii ◽  
C. Yoshii ◽  
Y. Kobatake ◽  
K. Kurihara
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Xenopus Laevis ◽  
High Sensitivity ◽  
Basic Amino Acid ◽  
Gustatory Receptors ◽  
Basic Amino Acids ◽  
Neutral Amino Acids ◽  
Gustatory Nerve ◽  
Cross Adaptation

The gustatory nerve responses of the aquatic toad Xenopus laevis to salts, acids, amino acids, and bitter substances were recorded. 1) The gustatory receptors were sensitive to amino acids and bitter substances. The thresholds were 10(-7) M for Arg, 3 X 10(-9) M for strychnine, and 3 X 10(-8) M for quinine, 200-20,000 times lower than the thresholds for the respective stimuli in the bullfrog. 2) The basic and the neutral amino acids were effective whereas the acidic ones were not. Relations between the responses and log stimulus concentrations for the basic amino acids were linear in a wide concentration range whereas those for the neutral ones were of S shape. Cross-adaptation did not occur among pairs of a basic amino acid and a neutral one. 3) Responses to the basic amino acids and the basic bitter substances were suppressed by the addition of salts to the stimulating solutions, while those to the neutral and the acidic substances were not suppressed.

In vivo inhibition of tyrosine uptake into rat retina by large neutral but not acidic amino acids

1986 ◽  
Vol 251 (4) ◽  
pp. E393-E399 ◽  
Author(s):  
M. H. Fernstrom ◽  
E. A. Volk ◽  
J. D. Fernstrom
Keyword(s):  
Amino Acids ◽  
Branched Chain Amino Acids ◽  
Rat Retina ◽  
Large Neutral Amino Acids ◽  
Neutral Amino Acids ◽  
Acidic Amino Acids ◽  
Tyrosine Uptake ◽  
Branched Chain ◽  
Serum Ratio

The uptake of tyrosine into rat retina and brain was studied in vivo after its peripheral injection alone or in combination with other amino acids. Both retinal and brain tyrosine levels increased monotonically for at least 60 min after tyrosine administration. When tyrosine was injected along with branched-chain amino acids, but not with acidic amino acids, such increments in retinal and brain tyrosine levels were significantly attenuated. The postinjection tyrosine levels in retina and brain paralleled better the serum ratio of tyrosine to the sum of the other large neutral amino acids (which include the branched-chain amino acids) than the serum tyrosine level alone. These results suggest that tyrosine uptake into rat retina, like that into brain, is mediated by a competitive transport system shared among the large neutral amino acids.

scholarly journals Electro-olfactogram and multiunit olfactory receptor responses to complex mixtures of amino acids in the channel catfish, Ictalurus punctatus.

1991 ◽  
Vol 98 (4) ◽  
pp. 699-721 ◽  
Author(s):  
J S Kang ◽  
J Caprio
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Binary Mixtures ◽  
Ictalurus Punctatus ◽  
Channel Catfish ◽  
Olfactory Receptor ◽  
Complex Mixtures ◽  
Neutral Amino Acids ◽  
Acidic Amino Acids ◽  
Receptor Sites

In vivo electrophysiological recordings from populations of olfactory receptor neurons in the channel catfish, Ictalurus punctatus, clearly showed that both electro-olfactogram and integrated neural responses of olfactory receptor cells to complex mixtures consisting of up to 10 different amino acids were predictable with knowledge of (a) the responses to the individual components in the mixture and (b) the relative independence of the respective receptor sites for the component stimuli. All amino acid stimuli used to form the various mixtures were initially adjusted in concentration to provide approximately equal response magnitudes. Olfactory receptor responses to both multimixtures and binary mixtures were recorded. Multimixtures were formed by mixing equal aliquots of 3-10 different amino acids. Binary mixtures were formed by mixing equal aliquots of two equally stimulatory solutions. Solution 1 contained either one to nine different neutral amino acids with long side-chains (LCNs) or one to five different neutral amino acids with short side-chains (SCNs). Solution 2, comprising the binary mixture, consisted of only a single stimulus, either a LCN, SCN, basic, or acidic amino acid. The increasing magnitude of the olfactory receptor responses to mixtures consisting of an increasing number of neutral amino acids indicated that multiple receptor site types with highly overlapping specificities exist to these compounds. For both binary mixtures and multimixtures composed of neutral and basic or neutral and acidic amino acids, the receptor responses were significantly enhanced compared with those mixtures consisting of an equal number of only neutral amino acids. These results demonstrate that receptor sites for the basic and acidic amino acids, respectively, are highly independent of those for the neutral amino acids, and suggest that a mechanism for synergism is the simultaneous activation of relatively independent receptor sites by the components in the mixture. In contrast, there was no evidence for the occurrence of mixture suppression.

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