We present the first presteady state kinetic analysis of an S-adenosylmethionine-dependent enzyme. The target enzyme is the bacterial EcoRI DNA methyl-transferase, which transfers the methyl group to the second adenine in the DNA sequence GAATTC. The rate constant for conversion of the central complex (enzyme-DNA-S-adenosylmethionine) to products (enzyme-methylated DNA-S-adenosylhomocysteine) (...

We identified and characterized a methyl transfer activity of the toluate cis-dihydrodiol (4-methyl-3,5-cyclohexadiene-cis-1, 2-diol-1-carboxylic acid) dehydrogenase of the TOL plasmid pWW0 towards toluene cis-dihydrodiol (3-methyl-4,5-cyclohexadiene-cis-1, 2-diol). When the purified enzyme from the recombinant Escherichia coli containing the xylL gene was incubated with toluene cis-dihydrodiol...

in order to increase the rate of gas absorption, chemical reaction in the liquid phase is considered. the purpose of this paper was to simulate gas absorption process by a liquid film over a spherical packing incorporating eddy viscosity and diffusivity. second order chemical reaction for two different cases (fast and slow) were considered. the system partial differential equations obtained was...

The remarkable selectivity of N-methyl mesoporphyrin IX (NMM) for G-quadruplexes (GQs) is long known, however its ability to stabilize and bind GQs has not been investigated in detail. Through the use of circular dichroism, UV-visible spectroscopy and fluorescence resonance energy transfer (FRET) melting assay we have shown that NMM stabilizes human telomeric DNA dAG(3)(TTAG(3))(3) (Tel22) and ...

The transfer of the methyl group from methylcobalamin to diaquocobinamide in aqueous solution has been demonstrated by proton, carbon-13, and phosphorus-31 nuclear magnetic resonance spectroscopy. The products of this reaction are aquocobalamin and the methylaquocobinamides. Dicyanocobinamide and the cyanoaquocobinamides do not serve as methyl acceptors, while ligands such as pyridine and histi...

The mode-specific vibrational energy relaxation of the amide I' and amide II' modes in NMA-d(1)/(D(2)O)(n) (n = 0-3) clusters were studied using the time-dependent perturbation theory at the B3LYP/aug-cc-pvdz level. The amide modes were identified for each cluster based on the potential energy distribution of each mode. The vibrational population relaxation time constants were derived for the a...

Reactions occurring at a carbon atom through the Walden inversion mechanism are one of the most important and useful classes of reactions in chemistry. Here we report an accurate theoretical study of the simplest reaction of that type: the H+CH4 substitution reaction and its isotope analogues. It is found that the reaction threshold versus collision energy is considerably higher than the barrie...

A very important trend for studying biomolecules is computational chemistry. In particular, nowadays it is possible to use theoretical methods to figure out the catalytic mechanism of enzyme reactions. Quantum chemistry has become a powerful tool to achieve a description of biological processes in enzymes active sites and to model reaction mechanisms. The present thesis uses Density Functional ...