Search results for "binding"

Discrete bond model (DBM) of sodium silicate glasses derived from XPS, Raman and NMR measurements

1993

In sodium silicate glasses, the fraction of differently bound Si species Q[i] (i = 0−4), depending on the number i of bridging oxygens bound to the quarternary silicon, is a function of stoichiometry and the Na/Si ratio. Sodium silicate glasses were investigated by high resolution X-ray photoelectron spectroscopy. To explain the differences in chemical shifts and linewidths of the O 1s signal of the bridging and the non-bridging oxygen as a function of alkali concentration, and extended glass model was developed. This new model takes into account the influence of the alkali concentration on the Q[i] distribution and on the appearance and concentrations of differently bound bridging oxygens …

Bioactivation of the Fungal Phytotoxin 2,5-Anhydro-D-glucitol by Glycolytic Enzymesisan Essential Component of itsMechanism of Action

2002

An isolate of Fusarium solani, NRRL 18883, produces the natural phytotoxin 2,5-anhydro-ᴅ-glucitol (AhG). This fungal metabolite inhibited the growth of roots (I50 of 1.6 mᴍ), butit did nothave any in vitro inhibitory activity. The mechanism of action of AhG requires enzymatic phosphorylation by plant glycolytic kinases to yield AhG-1,6-bisphosphate (AhG-1,6- bisP), an inhibitor of Fru-1,6-bisP aldolase. AhG-1,6-bisP had an I50 value of 570 μᴍ on aldolase activity, and it competed with Fru-1,6-bisP for the catalytic site on the enzyme, with a Ki value of 103 μᴍ. The hydroxyl group on the anomeric carbon of Fru-1,6-bisP is required for the formation of an essential covalent bond to ζ amino fu…

Substituent effects on axle binding in amide pseudorotaxanes: comparison of NMR titration and ITC data with DFT calculations

2012

The binding behaviour of differently substituted diamide axle molecules to Hunter/Vögtle tetralactam macrocycles was studied with a combination of NMR titration, isothermal titration calorimetry (ITC) experiments and calculations employing density functional theory (DFT), along with dispersion-corrected exchange-correlation functionals. Guests with alkyl or alkenyl chains attached to the diamide carbonyl groups have a significantly higher binding affinity to the macrocycle than guests with benzoyl amides and their substituted analogues. While the binding of the benzoyl and alkenyl substituted axles is enthalpically driven, the alkyl-substituted guest binds mainly because of a positive bindi…

Cooperative Binding of Divalent Diamides by N-Alkyl Ammonium Resorcinarene Chlorides

2015

N-Alkyl ammonium resorcinarene chlorides, stabilized by an intricate array of hydrogen bonds leading to a cavitand-like structure, bind amides. The molecular recognition occurs through intermolecular hydrogen bonds between the carbonyl oxygen and the amide hydrogen of the guests and the cation-anion circular hydrogen-bonded seam of the hosts, as well as through CH⋅⋅⋅π interactions. The N-alkyl ammonium resorcinarene chlorides cooperatively bind a series of di-acetamides of varying spacer lengths ranging from three to seven carbons. Titration data fit either a 1:1 or 2:1 binding isotherm depending on the spacer lengths. Considering all the guests possess similar binding motifs, the first bin…

Dehydroepiandrosterone Induction of the Abcd2 and Abcd3 Genes encoding peroxisomal ABC Transporters

2003

Dehydroepiandrosterone (DHEA) is a peroxisome proliferator known to increase the expression of the genes encoding the peroxisomal s-oxidation enzymes in rodents. Using RT-PCR, we analysed the expression of the Abcd2 and Abcd3 genes encoding the peroxisomal ABC transporters ALDRP (ALD related protein) and PMP70 (70 kDa peroxisomal membrane protein) in primary cultures of rats hepatocytes treated with sulfated DHEA. We observed a time (12-72h) and dose (125-500μM) dependent increase in the expression of both genes.

Digestion and absorption of polyunsaturated fatty acids

1991

Polyunsaturated fatty acids play an important part in the structure and function of cellular membranes and are precursors of lipid mediators which play a key role in cardiovascular and inflammatory diseases. Dietary sources of essential fatty acids are vegetable oils for either linoleic or alpha-linolenic acids, and sea fish oils for eicosapentaenoic and docosahexaenoic acids. Because of the specificity of the pancreatic lipid hydrolases, triglyceride fatty acid distribution is an essential parameter in the digestibility of fats. The efficiency of the intestinal uptake depends on the hydrolysis and especially on their micellarization. n-3 polyunsaturated fatty acid ethyl ester digestion is …

Erratum to: “Identification of a peptide mimicking the binding pattern of an antiphospholipid antibody”

2006

Affinity Cleavage of Carbamoyl-Phosphate Synthetase I Localizes Regions of the Enzyme Interacting with the Molecule of ATP that Phosphorylates Carbam…

1995

Two ATP molecules are used in the reaction catalyzed by carbamoyl-phosphate synthetase I. One molecule (ATPA) phosphorylates HCO3- and the other (ATPB) phosphorylates carbamate. Carbamoyl-phosphate synthetase I is a 160-kDa polypeptide consisting of a 40-kDa N-terminal moiety and a 120-kDa C-terminal moiety, the latter being composed of two similar halves of molecular mass 60 kDa. We showed [Alonso, E., Cervera, J., Garcia-Espana, A., Bendala, E. & Rubio, V. (1992) J. Biol. Chem. 267, 4524-4532] that Fe.ATP bound at the site for ATPB catalyzes the oxidative inactivation of carbamoyl-phosphate synthetase I in a model oxidative system consisting of Fe3+, ascorbate, and O2, and we detected ATP…

Regulation of Farnesyl Diphosphate Synthase Gene Expression by Fatty Acids

2003

Cholesterol biosynthesis depends on the activity of regulatory enzymes, including the peroxisomal Farnesyl Diphosphate Synthase (FPPS ). Cholesterol regulates its own synthesis rate. Hence, as a response to cholesterol depletion, a feed back mechanism is activated, whereby sterol regulatory binding proteins (SREBPla, 1c and 2 ) are subjected to sequential proteolytic activation, which permits their interaction with specific DNA response elements from responsive genes. In turn, the transcriptional activity of cholesterol biosynthesis genes is induced. Conversely, cholesterol accumulation decreases SREBP maturation and transcription of controlled genes. In addition, polyunsaturated fatty acid…

Target Analogue Imprinted Polymers with Affinity for Folic Acid and Related Compounds

2001

Two approaches to synthesize molecularly imprinted polymers with affinity for folic acid and other substituted pteridines have been compared. In the first approach, the folic acid analogue methotrexate was used as template and functional monomers capable of generating selective binding sites were searched in a miniaturized screening system based on binding assessment in the batch mode. Highest selectivity was seen using 2-vinylpyridine as functional monomer, which was confirmed in the chromatographic mode for a batch synthesized on a gram scale. However, the retentivity and selectivity of this phase were insufficient for anticipated applications. In a second approach, using methacrylic acid…