Ammonia toxicity under hyponatremic conditions in astrocytes: De novo synthesis of amino acids for the osmoregulatory response

2005 ◽  
Vol 47 (1-2) ◽  
pp. 39-50 ◽  
Author(s):  
C ZWINGMANN ◽  
D LEIBFRITZ
Keyword(s):  
Amino Acids ◽  
De Novo ◽  
Ammonia Toxicity ◽  
De Novo Synthesis

scholarly journals An enzymatic activation of formaldehyde for nucleotide methylation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Charles Bou-Nader ◽  
Frederick W. Stull ◽  
Ludovic Pecqueur ◽  
Philippe Simon ◽  
Vincent Guérineau ◽  
...  
Keyword(s):  
Amino Acids ◽  
Thymidylate Synthase ◽  
Active Site ◽  
De Novo ◽  
Crystallographic Structure ◽  
De Novo Synthesis ◽  
Active Site Residues ◽  
Enzymatic Activation ◽  
Enzyme Cofactors ◽  
Unique Ability

AbstractFolate enzyme cofactors and their derivatives have the unique ability to provide a single carbon unit at different oxidation levels for the de novo synthesis of amino-acids, purines, or thymidylate, an essential DNA nucleotide. How these cofactors mediate methylene transfer is not fully settled yet, particularly with regard to how the methylene is transferred to the methylene acceptor. Here, we uncovered that the bacterial thymidylate synthase ThyX, which relies on both folate and flavin for activity, can also use a formaldehyde-shunt to directly synthesize thymidylate. Combining biochemical, spectroscopic and anaerobic crystallographic analyses, we showed that formaldehyde reacts with the reduced flavin coenzyme to form a carbinolamine intermediate used by ThyX for dUMP methylation. The crystallographic structure of this intermediate reveals how ThyX activates formaldehyde and uses it, with the assistance of active site residues, to methylate dUMP. Our results reveal that carbinolamine species promote methylene transfer and suggest that the use of a CH2O-shunt may be relevant in several other important folate-dependent reactions.

scholarly journals De Novo Synthesis of Amino Acids by the Ruminal Bacteria Prevotella bryantii B14,Selenomonas ruminantium HD4, and Streptococcus bovis ES1

1998 ◽  
Vol 64 (8) ◽  
pp. 2836-2843 ◽  
Author(s):  
Cengiz Atasoglu ◽  
Carmen Valdés ◽  
Nicola D. Walker ◽  
C. James Newbold ◽  
R. John Wallace
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
De Novo ◽  
Dependent Manner ◽  
Streptococcus Bovis ◽  
De Novo Synthesis ◽  
Ruminal Bacteria ◽  
Total N ◽  
Selenomonas Ruminantium ◽  
Prevotella Bryantii

ABSTRACT The influence of peptides and amino acids on ammonia assimilation and de novo synthesis of amino acids by three predominant noncellulolytic species of ruminal bacteria, Prevotella bryantii B14, Selenomonas ruminantiumHD4, and Streptococcus bovis ES1, was determined by growing these bacteria in media containing 15NH4Cl and various additions of pancreatic hydrolysates of casein (peptides) or amino acids. The proportion of cell N and amino acids formed de novo decreased as the concentration of peptides increased. At high concentrations of peptides (10 and 30 g/liter), the incorporation of ammonia accounted for less than 0.16 of bacterial amino acid N and less than 0.30 of total N. At 1 g/liter, which is more similar to peptide concentrations found in the rumen, 0.68, 0.87, and 0.46 of bacterial amino acid N and 0.83, 0.89, and 0.64 of total N were derived from ammonia by P. bryantii, S. ruminantium, andS. bovis, respectively. Concentration-dependent responses were also obtained with amino acids. No individual amino acid was exhausted in any incubation medium. For cultures of P. bryantii, peptides were incorporated and stimulated growth more effectively than amino acids, while cultures of the other species showed no preference for peptides or amino acids. Apparent growth yields increased by between 8 and 57%, depending on the species, when 1 g of peptides or amino acids per liter was added to the medium. Proline synthesis was greatly decreased when peptides or amino acids were added to the medium, while glutamate and aspartate were enriched to a greater extent than other amino acids under all conditions. Thus, the proportion of bacterial protein formed de novo in noncellulolytic ruminal bacteria varies according to species and the form and identity of the amino acid and in a concentration-dependent manner.

A de novo Synthesis of Oxindoles from Cyclohexanone-Derived γ-Keto-ester Acceptors Using a Desaturative Amination–Cyclization Approach

Synthesis ◽  
2021 ◽  
Author(s):  
Henry P. Caldora ◽  
Sebastian Govaerts ◽  
Shashikant U. Dighe ◽  
Oliver J. Turner ◽  
Daniele Leonori
Keyword(s):  
Amino Acids ◽  
Primary Amine ◽  
De Novo ◽  
Building Blocks ◽  
De Novo Synthesis ◽  
Keto Ester ◽  
Mild Conditions ◽  
Blockbuster Drug

Here we report a desaturative approach for oxindole synthesis. This method uses simple γ-ester-containing cyclohexanones and primary amine building blocks as coupling partners. A dual photoredox–cobalt manifold is used to generate a secondary aniline that, upon heating, cyclizes with the pendent ester functionality. The process operates under mild conditions and was applied to the modification of several amino acids, the blockbuster drug mexiletine, as well as the formation of dihydroquinolinones.

scholarly journals Inhibiting Methanogenesis Stimulated de novo Synthesis of Microbial Amino Acids in Mixed Rumen Batch Cultures Growing on Starch but not on Cellulose

2020 ◽  
Vol 8 (6) ◽  
pp. 799
Author(s):  
Emilio M. Ungerfeld ◽  
M. Fernanda Aedo ◽  
Camila Muñoz ◽  
Natalie L. Urrutia ◽  
Emilio D. Martínez ◽  
...  
Keyword(s):  
Amino Acids ◽  
De Novo ◽  
Nitrogen Sources ◽  
Environmental Benefits ◽  
De Novo Synthesis ◽  
Protein Nitrogen ◽  
Protein Supplements ◽  
Batch Cultures ◽  
Sufficient Energy ◽  
Ruminant Diets

Ameliorating methane (CH4) emissions from ruminants would have environmental benefits, but it is necessary to redirect metabolic hydrogen ([H]) toward useful sinks to also benefit animal productivity. We hypothesized that inhibiting rumen methanogenesis would increase de novo synthesis of microbial amino acids (AA) as an alternative [H] sink if sufficient energy and carbon are provided. We examined the effects of inhibiting methanogenesis with 9, 10-anthraquione (AQ) on mixed rumen batch cultures growing on cellulose or starch as sources of energy and carbon contrasting in fermentability, with ammonium (NH4+) or trypticase (Try) as nitrogen (N) sources. Inhibiting methanogenesis with AQ inhibited digestion with cellulose but not with starch, and decreased propionate and increased butyrate molar percentages with both substrates. Inhibiting methanogenesis with 9, 10-anthraquinone increased de novo synthesis of microbial AA with starch but not with cellulose. The decrease in the recovery of [H] caused by the inhibition of methanogenesis was more moderate with starch due to an enhancement of butyrate and AA as [H] sinks. There may be an opportunity to simultaneously decrease the emissions of CH4 and N with some ruminant diets and replace plant protein supplements with less expensive non-protein nitrogen sources such as urea.

Transmembrane transport and intracellular kinetics of amino acids in human skeletal muscle

1995 ◽  
Vol 268 (1) ◽  
pp. E75-E84 ◽  
Author(s):  
G. Biolo ◽  
R. Y. Fleming ◽  
S. P. Maggi ◽  
R. R. Wolfe
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Human Skeletal Muscle ◽  
De Novo ◽  
Transmembrane Transport ◽  
Acid Transport ◽  
De Novo Synthesis ◽  
Intracellular Amino Acid

We have used stable isotopic tracers of amino acids to measure in vivo transmembrane transport of phenylalanine, leucine, lysine, alanine, and glutamine as well as the rates of intracellular amino acid appearance from proteolysis, de novo synthesis, and disappearance to protein synthesis in human skeletal muscle. Calculations were based on data obtained by the arteriovenous catheterization of the femoral vessels and muscle biopsy. We found that the fractional contribution of transport from the bloodstream to the total intracellular amino acid appearance depends on the individual amino acid, varying between 0.63 +/- 0.02 for phenylalanine and 0.22 +/- 0.02 for alanine. Rates of alanine and glutamine de novo synthesis were approximately eight and five times their rate of appearance from protein breakdown, respectively. The model-derived rate of protein synthesis was highly correlated with the same value calculated by means of the tracer incorporation technique. Furthermore, amino acid transport rates were in the range expected from literature values. Consequently, we conclude that our new model provides a valid means of quantifying the important aspects of protein synthesis, breakdown, and amino acid transport in human subjects.

S-deficiency responsive accumulation of amino acids is mainly due to hydrolysis of the previously synthesized proteins - not to de novo synthesis inBrassica napus

2012 ◽  
Vol 147 (3) ◽  
pp. 369-380 ◽  
Author(s):  
Bok-Rye Lee ◽  
Sowbiya Muneer ◽  
Kil-Yong Kim ◽  
Jean-Christophe Avice ◽  
Alain Ourry ◽  
...  
Keyword(s):  
Amino Acids ◽  
De Novo ◽  
De Novo Synthesis ◽  
S Deficiency ◽  
Hydrolysis Of

Nutrient utilization in actinomycetes. Induction of α-glucosidases in Streptomyces venezuelae

1981 ◽  
Vol 27 (7) ◽  
pp. 639-645 ◽  
Author(s):  
S. Chatterjee ◽  
L. C. Vining
Keyword(s):  
Amino Acids ◽  
Organic Acids ◽  
Ribonucleic Acid ◽  
De Novo ◽  
Nutrient Utilization ◽  
Enzyme Synthesis ◽  
De Novo Synthesis ◽  
Streptomyces Venezuelae ◽  
Messenger Ribonucleic Acid ◽  
Glucosidase Activity

Streptomyces venezuelae contains intracellular α-glucosidases that are induced during growth on maltose, isomaltose, maltotriose, dextrin, starch, and other α-glucosides. Induction was prevented by rifampicin at 10 μg∙mL−1 and inhibited by chloramphenicol or streptomycin, indicating that de novo synthesis of messenger ribonucleic acid and protein was required. Glucose and other readily utilizable sugars did not repress induction of α-glucosidase activity whereas certain organic acids and amino acids effectively reduced enzyme synthesis. Extracts of mycelium grown in the presence of maltose as an inducer hydrolysed maltose and isomaltose rapidly. Sucrose and other α-glucosides were less suitable substrates whereas trehalose and starch were not hydrolysed. No activity was observed with β-glucosides, α-galactosides, or methyl α-mannoside.

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