The effect of Ni(II), Cu(II) and Zn(II) association on the diketo/keto-enol tautomerism of thymine has been investigated through the use of B3LYP density functional theory calculations. Final energies were obtained at the B3LYP/6-311+G(2df,2p)//B3LYP/6-311+G(d,p) level of theory. Ni(II) and Cu(II) lead to an oxidation of thymine which for Zn(ii) is only partial and catalyze the tautomerization ...

Palladium (II) coordination complexes catalyze the reaction of alcohols with ketones to yield ethers. During the catalytic cycle, the alcohol adds selectively to the β-carbon (anti-Markovnikov). In this work, mechanism and kinetics for the reaction of methanol with methyl vinyl ketone (MVK), being catalyzed by Pd, has been theoretically investigated in detail. Using quantum mechanical approach,...

Curcuminoids are a safe natural food coloring additive with anti-inflammatory, antioxidant, and anticarcinogenic activities. Although demethoxycurcumin is one of the major bioactive constituents of curcuminoids, knowledge about its metabolic fate is scant. In the present study, four new metabolites, 5-dehydroxy-hexahydro-demethoxycurcumin-A (M-1), 5-dehydroxy-hexahydro-demethoxycurcumin-B (M-2)...

In combustion, enols can undergo keto-enol tautomerizations, which are intermediate steps in the formation of pollutant species. this work, we performed a theoretical kinetic study step-wise propen-2-ol tautomerization catalyzed by hydrogen and hydroperoxyl radicals. Ab initio calculations at CCSD(T)/aug-cc-pVTZ//M06-2X/cc-pVTZ level were run, rate constants calculated using multistructural tor...

Dihydrofolate reductase (DHFR) catalyzes the NADPH-dependent reduction of dihydrofolate (DHF) to tetrahydrofolate (THF). An important step in the mechanism involves proton donation to the N5 atom of DHF. The inability to determine the protonation states of active site residues and substrate has led to a lack of consensus regarding the catalytic mechanism involved. To resolve this ambiguity, we ...

Studies of the non-enzymatic decarboxylation of /3-keto acids have shown that it is the keto form of the 8-keto acid which loses CO2 to form an enol of the product. This was demonstrated for dimethylacetoacetic acid by Pedersen (1) and for dimethyloxalacetic acid by Steinberger and Westheimer (2). These latter authors studied the catalytic effect of metal ions on the decarboxylation reaction an...

single walled nanotubes (swnt) are common interested nanovehicle to make biosensors more sensitive.carbon nanotubes (cnts) have many distinct properties make them to be exploited to develop the nextgeneration of such nano sensors .the keto-enol tautomerization is one of the most common investigatedsubjects of isomerism in this regards, sensors are devices that are able to detect and change the ...

Palladium (II) coordination complexes catalyze the reaction of alcohols with ketones to yield ethers. During the catalytic cycle, the alcohol adds selectively to the β-carbon (anti-Markovnikov). In this work, mechanism and kinetics for the reaction of methanol with methyl vinyl ketone (MVK), being catalyzed by Pd, has been theoretically investigated in detail. Using quantum mechanical approach,...

The biosynthesis pathway to diadinoxanthin and fucoxanthin was elucidated in Phaeodactylum tricornutum by a combined approach involving metabolite analysis identification of gene function. For the initial steps leading to β-carotene, putative genes were selected from the genomic database and the function of several of them identified by genetic pathway complementation in Escherichia coli. They ...