Macromolecules conformational changes

Thus, in dependence on the way of macromolecule conformation change, ratio of life times of salt bonds and correlation time of macromolecule segment rotation, change of local macromolecule units density, under formation of complex polyelectrolyte-SAS segment mobility of macromolecule may be increased, decreased or remains constant. 

Ion channel studies motivated Allen et al. [47] who have developed an elegant variational formalism to compute polarization charges induced on dielectric interfaces. They solved the variational problem with a steepest descent method and applied their formulation in molecular dynamics (MD) simulations of water permeation through nanopores in a polarizable membrane [48-50], Note that the functional chosen by Allen et al. [47] is not the only formalism that can be used. Polarization free energy functionals [51-53] are more appropriate for dynamical problems, such as macromolecule conformational changes and solvation [54-57],... 

In other cases, including those involving considerable deformation of macromolecules (conformational changes) in the flow, an inverse phenomenon constituting an increase in viscosity with increasing flow rate may also take place. This phenomenon can not be described in terms of the simplest rheological models with constant parameters. Systems in which viscosity is dependent on the strain rate are referred to as anomalous, or non-Newtonian fluids. In sufficiently dilute systems, i.e. in the absence of interactions between particles, changes in viscosity due to the orientation and deformation of dispersed particles are usually rather small. 

It is very difficult and scarce to find literature to study the electrokinetic phenomena of proteins or macromolecules in solution therefore limit us to the basic concepts of electrokinetic changes observed, they are conformational change because of the presence of salts and the zeta potential change in pH. 

Flacche, L. S., Washington, G. E., and Brant, D. A., Light scattering investigation of the temperature-driven conformation change in xanthan, Macromolecules, 20, 2179, 1987. 

Macromolecules differ from small molecules in a number of critical properties. First, the linear chain structure confers elasticity, toughness, and strength on the solid state system. This is a consequence of the reorientational freedom of the skeletal bonds and of their ability to absorb impact or undergo elastic deformation by means of conformational changes rather than bond cleavage. 

The mechanism of carcinogenesis by PAHs is believed to involve alkylation of an informational macromolecule in a critical, but at present unknown, manner. Such an interaction with a protein has been modelled by alkylation of a peptide this showed a conformational change occurred on alkylation. It has not yet been possible to study the structure of DNA alkylated by an activated carcinogen this is because DNA is a fiber and the structural order in it is not sufficient for a crystal structure determination. However the crystal structures of some alkylated portions of nucleic acids are described, particularly some nucleosides alkylated by chloromethyl derivatives of DMBA. In crystals of these alkylation products the PAH portion of the adduct shows a tendency to lie between the bases of other nucleoside... 

Conformational and phase transitions can potentially be indicative of the primary structure of thermosensitive macromolecules. Indeed, depending on the relative location of H- and P-blocks, as well as on the variation of their length, the chains can either undergo conformational transition accompanied by phase separation, or they can exhibit only the conformational changes without macroscopic phase transitions, i.e. the behaviour observed in the case of protein-like HP-copolymers. Therefore, the solution behaviour of separated fractions of these NVCl/NVIAz-copolymers in an aqueous medium at different temperatures is very important. 

Energy-transfer measurements are often used to estimate the distances between sites on biological macromolecules such as proteins, and the effects of conformational changes on these distances. In this type of experiment, the efficiency of energy transfer is used to calculate the distance between donor and acceptor fluorophores in order to obtain structural information about the macromolecule. 

Nilsson KPR, Inganas O (2004) Optical emission of a conjugated polyelectrolyte calcium-induced conformational changes in calmodulin and calmodulin-calcineurin interactions. Macromolecules 37 9109-9113... 

Characterization of ligand-induced conformational changes in atomic detail has primarily been studied through comparison of high-resolution X-ray structures for macromolecules crystallized in both free and ligand-bound states. The possibility of monitoring such... 

D. Genest and P. Wahl, in Dynamic Aspects of Conformational Change in Biological Macromolecules (C. Sadron, ed.), pp. 367-379, D. Reidel, Dordrecht, Holland (1973). 

Computer-based techniques for locating and analyzing ligand binding sites on macromolecules. These methods must take into account the steric and electrostatic properties of ligand and receptor as well as ligand-induced conformational changes. 

Membrane conformational changes are observed on exposure to anesthetics, further supporting the importance of physical interactions that lead to perturbation of membrane macromolecules. For example, exposure of membranes to clinically relevant concentrations of anesthetics causes membranes to expand beyond a critical volume (critical volume hypothesis) associated with normal cellular function. Additionally, membrane structure becomes disorganized, so that the insertion of anesthetic molecules into the lipid membrane causes an increase in the mobility of the fatty acid chains in the phospholipid bilayer (membrane fluidization theory) or prevent the interconversion of membrane lipids from a gel to a liquid form, a process that is assumed necessary for normal neuronal function (lateral phase separation hypothesis). 

Stefan Fischer, Curvilinear reaction-coordinates of conformal change in macromolecules application to rotamase catalysis , Ph. D. Thesis, Harvard University, (1992). 

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