2,566 research outputs found
Mg spin affects adenosinetriphosphate activity
The Schlegel-Frisch ab initio molecular dynamics (ADMP) (DFT:B3LYP), T = 310
K, is used to study complexation between adenosinetriphosphate (ATP), ATP
subsystem, and magnesium cofactor [Mg(H2O)6]2+, Mg subsystem, in a water pool,
modeled with 78 water molecules, in singlet (S) and triplet (T) states. The
computations prove that the way of ATP cleavage is governed by the electron
spin of Mg. In the S state Mg prefers chelation of \gamma-\beta-phosphate
oxygens (O1-O2), whereas in the T state it chelates \beta-\alpha-phosphate
oxygens (O2-O3) or produces a single-bonded intermediate. Unlike the chelates,
which initiate ionic reaction paths, the single-bonded intermediate starts off
a free-radical path of ATP cleavage, yielding a highly reactive
adenosinemonophosphate ion-radical, .AMP-, earlier observed in the CIDNP
(Chemically Induced Dynamic Nuclear Polarization) experiment (A.A. Tulub,
2006). The free-radical path is highly sensitive to Mg nuclear spin, which
through a hyperfine interaction favors the production of unpaired electron
spins. The unique role of Mg in ATP cleavage comes through its ability to serve
as a unique redox center, initially accepting an electron from ATP and then
giving it back to products. Redox activity of Mg differs for T and S states and
affects the number of coordinated water molecules. The findings give a new
insight into the NTP (N = nucleoside) energetics and assembly of NTP-operating
molecules, including proteins.Comment: 13 pages, 4 figure
The chromatographic identification of some biologically important phosphate esters
the objective of the present work was to provide a means for separating and indentifying phosphate esters involved in glycolysis in higher plants. Paper chromatography of phosphate esters has been employed by several workers, most notably Benson et al. (1) and Hanes and Isherwood (2). Benson's procedures were not primarily designed for identification of phosphate esters and gave low Rr values for the phosphate compounds of particular interest to us. The unidimensional methods of Hanes and Isherwood do not result in adequate resolution of the complex mixtures such as are obtained from our plant materials.
The present procedure is based on two-dimensional chromatography with successive development in an acid and in a basic solvent. The solvents finally selected gave the best over-all resolution of the intermediates involved in plant glycolysis. Undoubtedly the resolution of certain pairs of compounds may be improved by suitable modifications. We have in addition made certain improvements in the procedure for locating the chromatographed materials
Use of the enzyme hexokinase for the reduction of inherent light levels
Use of enzyme hexokinase and glucose to reduce inherent light levels of ATP in luciferase composition
Soliton structures in a molecular chain model with saturation
In the present work, we study, by means of a one-dimensional lattice model,
the collective excitations corresponding to intra molecular ones of a chain
like proteins. It is shown that such excitations are described by the Nonlinear
Schrodinger equation with saturation. The solutions obtained here are the bell
solitons, bubbles, kinks and crowdons. Since they belong to different sectors
on the parametric space, the bubble condensation could give place to some
important changes of face in this kind of nonlinear system. Additionally, it is
shown that the limiting velocity of the solitons is the velocity of sound waves
corresponding to longitudinal vibrations of molecules.Comment: 12 pages, 4 figure
Protein sterilization method of firefly luciferase using reduced pressure and molecular sieves
The sterilization of the protein fruitfly luciferase under conditions that prevent denaturation is examined. Denaturation is prevented by heating the protein in contact with molecular seives and under a reduced pressure of the order of 0.00005 millimeters of mercury
Thin film models for active gels
In this study we present a free-boundary problem for an active liquid crystal
based on the Beris-Edwards theory that uses a tensorial order parameter and
includes active contributions to the stress tensor to analyse the rich defect
structure observed in applications such as the Adenosinetriphosphate (ATP)
driven motion of a thin film of an actin filament network. The small aspect
ratio of the film geometry allows for an asymptotic approximation of the
free-boundary problem in the limit of weak elasticity of the network and strong
active terms. The new thin film model captures the defect dynamcs in the bulk
as well as wall defects and thus presents a significant extension of previous
models based on the Lesli-Erickson-Parodi theory. Analytic expression are
derived that reveal the interplay of anchoring conditions, film thickness and
active terms and their control of transitions of flow structure.Comment: 33 pages, 3 figure
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