Chemically Selective Reactions in Confined Spaces in Hybrid Aerogels

2005 ◽  
Vol 899 ◽  
Author(s):  
Xipeng Liu ◽  
Chunhua Yao ◽  
William M Risen
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Metal Ions ◽  
Chemical Reactions ◽  
Reaction Products ◽  
Spatial Confinement ◽  
Confined Spaces ◽  
Hybrid Silica ◽  
Hybrid Aerogels ◽  
Chemically Selective

AbstractBy employing novel hybrid silica/functional polymer aerogels, control of the course of chemical reactions between reactants confined inside of the aerogels with reactants whose access to the confinement domain is controlled by diffusion has been explored. Thus, monolithic silica/biopolymer hybrid aerogels have been synthesized with coordinated metal ions that can react with amino acids, such as L-cysteine, that are provided externally in a surrounding solution. Metal ions, such as Au(III), that can react in solution with the amino acid to produce one set of products under a given set of stoichiometric or concentration conditions, and a different set of products under a second set of conditions, were selected for incorporation into the aerogel. It was discovered that the course of the reaction can be changed by spatial confinement of the reaction domain in the aerogel. For example, in the case of Au(III) and L-cysteine, the Au(III) ions are confined in nanoscale domains, and when they are reacted with the amino acid, the nature of the reaction products is controlled by diffusion of the L-cysteine into the domains. Exploration of these and related phenomena will be presented.

scholarly journals ywfE in Bacillus subtilis Codes for a Novel Enzyme, l-Amino Acid Ligase

2005 ◽  
Vol 187 (15) ◽  
pp. 5195-5202 ◽  
Author(s):  
Kazuhiko Tabata ◽  
Hajime Ikeda ◽  
Shin-ichi Hashimoto
Keyword(s):  
Amino Acids ◽  
Bacillus Subtilis ◽  
Amino Acid ◽  
High Performance ◽  
Consensus Sequence ◽  
Reaction Products ◽  
In Silico Screening ◽  
Vitro Assay ◽  
Hydrolysis Of

ABSTRACT The ATP-dependent carboxylate-amine/thiol ligase superfamily is known to contain enzymes catalyzing the formation of various types of peptide, such as d-alanyl-d-alanine, polyglutamate, and γ-peptide, but, curiously, no enzyme synthesizing α-dipeptides of l-amino acids is known. We attempted to find such an enzyme. By in silico screening based on the consensus sequence of the superfamily followed by an in vitro assay with purified enzyme to avoid the degradation of the peptide(s) synthesized, ywfE of Bacillus subtilis was found to code for the activity forming l-alanyl-l-glutamine from l-alanine and l-glutamine with hydrolysis of ATP to ADP. No AMP was formed, supporting the idea that the enzyme belongs to the superfamily. Surprisingly, the enzyme accepted a wide variety of l-amino acids. Among 231 combinations of l-amino acids tested, reaction products were obtained for 111 combinations and 44 kinds of α-dipeptides were confirmed by high-performance liquid chromatography analyses, while no tripeptide or longer peptide was detected and the d-amino acids were inert. From these results, we propose that ywfE encodes a new member of the superfamily, l-amino acid ligase.

scholarly journals System-directed pairing of protein amino acids. Part I

2021 ◽  
Author(s):  
Miloje M. Rakočević
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Genetic Code ◽  
Chemical Reactions ◽  
Review Paper ◽  
Point Of View ◽  
Second Phase ◽  
Protein Amino Acids ◽  
The Moment ◽  
Current Science

The idea of this review paper is as follows. If it can be shown (and it can!) that the pairing of protein amino acids is system-directed (determined), then the hypothesis of a prebiotically determined genetic code (Rakočević, 2004a) gets its full meaning. The hypothesis is supported by the fact that all these pairings come to the fore primarily through classes and subclasses of amino acid molecules. What is, however, unexpected and even unbelievable from the point of view of current science is the fact that the quantities, i.e. number of atoms (in a direct or indirect relation to the number of nucleons), in these classes and subclasses, are determined by Gauss’ number 51 (51 = 3 x 17), or Gauss’ sequence: 51 ± 10, 51 ± 20, 51 ± 30, 51 ± 40 and 51 ± 50; also by Dürer’s number 34 (34 = 2 x 17), even more either by its double value, 68; or by Dürer’s sequences: 34 ± 10, 34 ± 5 and 68 ± 10, 68 ± 5. Since the hypothesis refers to constituents – amino acids and nucleotides – it follows that in terms of the type and number of constituents, it makes no sense to talk about evolution of GC, but only about its generating. [Generated, not degenerated code!] It makes sense to talk about the evolution of the genetic code only from the "moment" when the resulting peptide and nucleotide chains enter into chemical reactions and interactions; although even then it can be said that this is just a second phase of GC generation.

Highly sensitive colorimetric detection of HgII and CuII in aqueous solutions: from amino acids toward solid platforms

The Analyst ◽  
2015 ◽  
Vol 140 (3) ◽  
pp. 744-749 ◽  
Author(s):  
Jooyoung Park ◽  
Byunggyu In ◽  
Lok Nath Neupane ◽  
Keun-Hyeung Lee
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Aqueous Solutions ◽  
Metal Ions ◽  
Colorimetric Detection ◽  
Selective Detection ◽  
Highly Sensitive ◽  
Fluorescence Change

A chemosensor (NBD-H) based on an amino acid with 7-nitro-2,1,3-benzoxadiazole was used for selective detection of HgII and CuII among 15 metal ions in aqueous solutions by a colorimetric change and fluorescence change.

Amino acid-modified chitosan nanoparticles for Cu2+ chelation to suppress CuO nanoparticle cytotoxicity

2017 ◽  
Vol 5 (19) ◽  
pp. 3521-3530 ◽  
Author(s):  
Yixian Zhang ◽  
Yiran Xu ◽  
Xiangyi Xi ◽  
Surakshya Shrestha ◽  
Pengfei Jiang ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Amino Acids ◽  
Amino Acid ◽  
Metal Ions ◽  
Chitosan Nanoparticles ◽  
Intracellular Reactive Oxygen Species ◽  
Engineered Nanoparticles ◽  
Oxygen Species ◽  
Modified Chitosan ◽  
Cuo Nanoparticle

Chitosan nanoparticles grafted with amino acids suppress the cytotoxicity of engineered nanoparticles by chelating intracellularly released metal ions and scavenging intracellular reactive oxygen species.

Dietary intake of tryptophan tied emotion-related impulsivity in humans

2019 ◽  
pp. 1-8 ◽  
Author(s):  
Florian Javelle ◽  
Descartes Li ◽  
Philipp Zimmer ◽  
Sheri L. Johnson
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Food Intake ◽  
Essential Amino Acid ◽  
Food Habits ◽  
Psychological Disorder ◽  
Serotonin Synthesis ◽  
Amino Acid Tryptophan ◽  
Pass Through ◽  
Three Factor

Abstract. Emotion-related impulsivity, defined as the tendency to say or do things that one later regret during periods of heightened emotion, has been tied to a broad range of psychopathologies. Previous work has suggested that emotion-related impulsivity is tied to an impaired function of the serotonergic system. Central serotonin synthesis relies on the intake of the essential amino acid, tryptophan and its ability to pass through the blood brain barrier. Objective: The aim of this study was to determine the association between emotion-related impulsivity and tryptophan intake. Methods: Undergraduate participants (N = 25, 16 women, 9 men) completed a self-rated measure of impulsivity (Three Factor Impulsivity Index, TFI) and daily logs of their food intake and exercise. These data were coded using the software NutriNote to evaluate intakes of tryptophan, large neutral amino acids, vitamins B6/B12, and exercise. Results: Correlational analyses indicated that higher tryptophan intake was associated with significantly lower scores on two out of three subscales of the TFI, Pervasive Influence of Feelings scores r =  –.502, p < . 010, and (lack-of) Follow-Through scores, r =  –.407, p < . 050. Conclusion: Findings provide further evidence that emotion-related impulsivity is correlated to serotonergic indices, even when considering only food habits. It also suggests the need for more research on whether tryptophan supplements might be beneficial for impulsive persons suffering from a psychological disorder.

Purification of Antihemophilic Factor (Factor VIII) by Amino Acid Precipitation*

1964 ◽  
Vol 11 (01) ◽  
pp. 064-074 ◽  
Author(s):  
Robert H Wagner ◽  
William D McLester ◽  
Marion Smith ◽  
K. M Brinkhous
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Factor Viii ◽  
Plasma Protein ◽  
Acid Precipitation ◽  
Aminobutyric Acid ◽  
Gamma Aminobutyric Acid ◽  
Specific Procedure ◽  
Beta Alanine ◽  
Antihemophilic Factor

Summary1. The use of several amino acids, glycine, alpha-aminobutyric acid, alanine, beta-alanine, and gamma-aminobutyric acid, as plasma protein precipitants is described.2. A specific procedure is detailed for the preparation of canine antihemophilic factor (AHF, Factor VIII) in which glycine, beta-alanine, and gammaaminobutyric acid serve as the protein precipitants.3. Preliminary results are reported for the precipitation of bovine and human AHF with amino acids.

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