Search results for "acids"

Sequestration of biogenic amines by alginic and fulvic acids.

2006

The interaction of natural (alginic and fulvic acids) and synthetic (polyacrylic acid 2.0 kDa) polyelectrolytes with some protonated polyamines [diamines: ethylendiamine, 1,4-diaminobutane (or putrescine), 1,5-diaminopentane (or cadaverine); triamines: N-(3-aminopropyl)-1,4diaminobutane (or spermidine), diethylenetriamine; tetramine: N.N'-bis(3-aminopropyl)-1,4-diaminobutane (or spermine); pentamine: tetraethylene-pentamine; hexamine: pentaethylenehexamine] was studied at T=25 degrees C by potentiometry and calorimetry. Measurements were performed without supporting electrolyte, in order to avoid interference, and results were reported at I=0 mol L(-1). For all the systems, the formation of…

Polysarcosine-Based Lipids: From Lipopolypeptoid Micelles to Stealth-Like Lipids in Langmuir Blodgett Monolayers.

2016

Amphiphiles and, in particular, PEGylated lipids or alkyl ethers represent an important class of non-ionic surfactants and have become key ingredients for long-circulating (“stealth”) liposomes. While poly-(ethylene glycol) (PEG) can be considered the gold standard for stealth-like materials, it is known to be neither a bio-based nor biodegradable material. In contrast to PEG, polysarcosine (PSar) is based on the endogenous amino acid sarcosine (N-methylated glycine), but has also demonstrated stealth-like properties in vitro, as well as in vivo. In this respect, we report on the synthesis and characterization of polysarcosine based lipids with C14 and C18 hydrocarbon chains and their end g…

Prostaglandin E2 and prostaglandin F2 alpha as endometrial receptivity biomarkers in successful embryo implantation

2014

Failure in the adhesion of the human blastocyst to the endometrium has been described as an important cause of infertility. Establishing the period of the so-called window of implantation and understanding the molecular mechanisms associated with embryo implantation has clinical and scientific implications. While over the last decades histological evaluation has been used to determine the phase of the menstrual cycle of the endometrium, the poor information obtained has made the case of using new technologies to identify specific markers, understand and characterize the receptive stage. This doctoral thesis investigates the existence, function and clinical impact of two specific lipids, the…

The contribution of methyl groups dynamics to the dynamical transition of proteins

2008

Transport of Arabidopsis GPI-anchored proteins along the early secretory pathway: Role of GPI-anchor remodelling and p24 proteins

2019

Las proteínas con anclaje GPI son una familia de proteínas que están ancladas a la cara exterior de la membrana plasmática mediante un ancla GPI y se ha visto que juegan un papel clave en plantas. Sin embargo, la maquinaria molecular implicada en el transporte de estas proteínas a la membrana plasmática en plantas es aún desconocida. Las proteínas p24 tienen un papel importante en el control de calidad de proteínas (posiblemente incluyendo las proteínas con anclaje GPI) transportadas entre el Retículo Endoplasmático y el aparato de Golgi. Esta tesis doctoral tiene como objetivo el estudio de la posible implicación de las proteínas p24 en la salida del Retículo Endoplasmático y en la localiz…

Synthesis and characterization of a new set of protic ionic liquids

2012

Exploring fast proton transfer events associated with lateral proton diffusion on the surface of membranes

2019

Proton diffusion (PD) across biological membranes is a fundamental process in many biological systems, and much experimental and theoretical effort has been employed for deciphering it. Here, we report on a spectroscopic probe, which can be tightly tethered to the membrane, for following fast (nanosecond) proton transfer events on the surface of membranes. Our probe is composed of a photoacid that serves as our light-induced proton source for the initiation of the PD process. We use our probe to follow PD, and its pH dependence, on the surface of lipid vesicles composed of a zwitterionic headgroup, a negative headgroup, a headgroup that is composed only from the negative phosphate group, or…

(2-Pyridyl)sulfonyl Groups for ortho -Directing Palladium- Catalyzed Carbon-Halogen Bond Formation at Functionalized Arenes

2017

International audience; We describe an efficient palladium-catalyzed selective C-H ortho-monohalogenation (X=I, Br, Cl, F) of various functionalized (2-pyridyl) aryl-sulfones. ortho-, meta-and para-functionalization is tolerated at the arene group which undergoes C-H halogenation. Some modifications are also possible on the 2-(arylsulfonyl) heteroaryl directing groups. A comparison of the halogenation efficiency suggests that bromination is the practical method of choice, while chlorination and fluorination are possible but more challenging. Under forcing conditions ortho-dihalogenation can also be achieved.

Redox reaction between amino‐(3,4‐dihydroxyphenyl)methyl phosphonic acid and dopaquinone is responsible for the apparent inhibitory effect on tyrosin…

2002

Amino‐(3,4‐dihydroxyphenyl)methyl phosphonic acid, the phosphonic analog of 3,4‐dihydroxyphenylglycine, had been previously reported as a potent inhibitor of tyrosinase. The mechanism of the apparent enzyme inhibition by this compound has now been established. Amino‐(3,4‐dihydroxyphenyl)methyl phosphonic acid turned out to be a substrate and was oxidized to o‐quinone, which evolved to a final product identified as 3,4‐dihydroxybenzaldehyde, the same as for 3,4‐dihydroxyphenylglycine. Monohydroxylated compounds (amino‐(3‐hydroxyphenyl)methyl phosphonic acid and amino‐(4‐hydroxyphenyl)methyl phosphonic acid) were not oxidized, neither was 4‐hydroxy‐l‐phenylglycine. However, the relatively hig…

RAB18 Loss Interferes With Lipid Droplet Catabolism and Provokes Autophagy Network Adaptations

2020

Autophagy is dependent on appropriate lipid supply for autophagosome formation. The regulation of lipid acquisition and the autophagy network response to lipid-limiting conditions are mostly elusive. Here, we show that the knockout of the RAB GTPase RAB18 interferes with lipid droplet catabolism, causing an impaired fatty acid release. The resulting reduced lipid-droplet-derived lipid availability influences autophagy and provokes adaptive modifications of the autophagy network. These adjustments include increased expression and phosphorylation of ATG2B as well as augmented formation of the ATG12-ATG5 conjugate. Moreover, ATG9A shows an enhanced phosphorylation at amino acid residues tyrosi…