Adénosine triphosphate | EPFL Graph Search

L’adénosine triphosphate, ou ATP, est un nucléotide formé à partir d'un nucléoside associé à un triphosphate. Dans la biochimie de tous les êtres vivants connus, l'ATP fournit l'énergie nécessaire aux réactions chimiques du métabolisme, à la locomotion, à la division cellulaire, ou encore au transport actif d'espèces chimiques à travers les membranes biologiques. Afin de libérer cette énergie, la molécule d'ATP est clivée, par hydrolyse, en adénosine diphosphate (ADP) et en phosphate, réaction qui s'accompagne d'une variation d'enthalpie libre standard ΔrG°' de . Les cellules régénèrent ensuite l'ATP à partir de l'ADP essentiellement de trois manières différentes : par phosphorylation oxydative dans le cadre de la respiration cellulaire, par photophosphorylation dans le cadre de la photosynthèse, et par phosphorylation au niveau du substrat au cours de certaines réactions chimiques exergoniques, par exemple au cours de la glycolyse ou du cycle de Krebs. Ainsi, le corps humain ne conti

Chemistry of a-aminonitriles. Aldomerization of glycolaldehyde phosphate to rac-hexose 2,4,6-triphosphates and (in presence of formaldehyde) rac-pentose 2,4-diphosphates: rac-allose 2,4,6-triphosphate and rac-ribose 2,4-diphosphate are the main reaction products

Daniel Mueller

Glycoaldehyde phosphate aldomerizes in aq. NaOH to a product mixt. contg. the racemates of two diastereomeric tetrose 2,4-diphosphates and 8 hexose 2,4,5-triphosphates. The aldomerization of glycoaldehyde in the presence of formaldehyde is a variant of the formose reaction. It avoids the formation of complex formose product mixts., because C(2)-phosphorylated aldoses cannot undergo aldose-ketose tautomerization. This work, with its demonstration of an intrinsic kinetic preference for ribose 2,4-diphosphate and allose 2,4,5-triphosphate formation, adds a piece of factual chem. information to ongoing discussion about the origin of ribonucleic acids. [on SciFinder (R)]

1990

Chlorination of arenes via the degradation of toxic chlorophenols

Paul Joseph Dyson, Mingyang Liu, Xuemei Yang

Aryl chlorides are among the most versatile synthetic precursors, and yet inexpensive and benign chlorination techniques to produce them are underdeveloped. We propose a process to generate aryl chlorides by chloro-group transfer from chlorophenol pollutants to arenes during their mineralization, catalyzed by Cu(NO3)2/NaNO3 under aerobic conditions. A wide range of arene substrates have been chlorinated using this process. Mechanistic studies show that the Cu catalyst acts in cooperation with NOx species generated from the decomposition of NaNO3 to regulate the formation of chlorine radicals that mediate the chlorination of arenes together with the mineralization of chlorophenol. The selective formation of aryl chlorides with the concomitant degradation of toxic chlorophenol pollutants represents a new approach in environmental pollutant detoxication. A reduction in the use of traditional chlorination reagents provides another (indirect) benefit of this procedure.

2022

Sustained expression of PGC-1α in the rat nigrostriatal system selectively impairs dopaminergic function

Patrick Aebischer, Julien Dusonchet, Sylvain Eric Lengacher, Bernard Schneider

Mitochondrial dysfunction and oxidative stress have been implicated in the etiology of Parkinsons disease. Therefore, pathways controlling mitochondrial activity rapidly emerge as potential therapeutic targets. Here, we explore the neuronal response to prolonged overexpression of peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1), a transcriptional regulator of mitochondrial function, both in vitro and in vivo. In neuronal primary cultures from the ventral midbrain, PGC-1 induces mitochondrial biogenesis and increases basal respiration. Over time, we observe an increasing proportion of the oxygen consumed by neurons which are dedicated to adenosine triphosphate production. In parallel to enhanced oxidative phosphorylation, PGC-1 progressively leads to a decrease in mitochondrial polarization. In the adult rat nigrostriatal system, adeno-associated virus (AAV)-mediated overexpression of PGC-1 induces the selective loss of dopaminergic markers and increases dopamine (DA) catabolism, leading to a reduction in striatal DA content. In addition, PGC-1 prevents the labeling of nigral neurons following striatal injection of the fluorogold retrograde tracer. When PGC-1 is expressed at higher levels following intranigral AAV injection, it leads to overt degeneration of dopaminergic neurons. Finally, PGC-1 overexpression does not prevent nigrostriatal degeneration in pathologic conditions induced by -synuclein overexpression. Overall, we find that lasting overexpression of PGC-1 leads to major alterations in the metabolic activity of neuronal cells which dramatically impair dopaminergic function in vivo. These results highlight the central role of PGC-1 in the function and survival of dopaminergic neurons and the critical need for maintaining physiological levels of PGC-1 activity.

Oxford University Press2012

Sustained expression of PGC-1α in the rat nigrostriatal system selectively impairs dopaminergic function

Patrick Aebischer, Julien Dusonchet, Sylvain Eric Lengacher, Bernard Schneider

Oxford University Press2012