Directed conformational change

An alternative control would be direct interaction between the electron carrier protein and the protein exchanger, but it is not clear that there is sufficient oxidase available to interact by direct conformational change with the exchanger molecules. 

The ab initio calculations indicate that the bay-region PAHTC conformers with pseudo-diaxial orientation of the 1-OH and 2-OH group (structures 6 and 7) are energetically acceptable at room temperature and can be populated by directed conformational change, even if the pseudo-diequatorial conformers were favoured in aqueous solution [112]. This provides a quantum-theoretical rationale for the results of the AMBER force field calculations [112] presented below. 

Apart from the direct conformational changes in enzymes, which may occur at very high pressures, pressure affects enzymatic reaction rates in SCFs in two ways. First, the reaction rate constant changes with pressure according to transition stage theory and standard thermodynamics. Theoretically, one can predict the effect of pressure on reaction rate if the reaction mechanism, the activation volumes and the compressibility factors are known. Second, the reaction rates may change with the density of SCFs because physical parameters, such... 

The classical microscopic description of molecular processes leads to a mathematical model in terms of Hamiltonian differential equations. In principle, the discretization of such systems permits a simulation of the dynamics. However, as will be worked out below in Section 2, both forward and backward numerical analysis restrict such simulations to only short time spans and to comparatively small discretization steps. Fortunately, most questions of chemical relevance just require the computation of averages of physical observables, of stable conformations or of conformational changes. The computation of averages is usually performed on a statistical physics basis. In the subsequent Section 3 we advocate a new computational approach on the basis of the mathematical theory of dynamical systems we directly solve a... 

In the structure of unphosphorylated phosducin that binds to Gpy, Ser 73 points towards the flexible loop of phosducin and not towards Gpy it is, therefore, accessible on the surface for phosphorylation. Phosphorylation of Ser 73 cannot lead to the direct disruption of the phosducin/GpY interaction. Rather, the structure suggests that phosphorylation may lead to conformational changes in the N-terminal domain of phosducin, especially in the flexible loop region, that could weaken or alter the phosducin/GpY interface. 

DICR (depolarization-induced Ca2+ release) is Ca2+ release triggered by depolarization of the sarcolemma. In skeletal muscle, conformational change in the voltage sensor (a 1S subunit of the dihydropyridine receptor) in the T-tubule is directly transmitted to the... 

The NHR contains also the conserved Calcineurin docking site, PxlxIT, required for the physical interaction of NEAT and Calcineurin. Dephosphorylation of at least 13 serines residues in the NHR induces a conformational change that exposes the nuclear localization sequences (NLS), allowing the nuclear translocation of NEAT. Rephosphorylation of these residues unmasks the nuclear export sequences that direct transport back to the cytoplasm. Engagement of receptors such as the antigen receptors in T and B cells is coupled to phospholipase C activation and subsequent production of inositol triphosphate. Increased levels of inositol triphosphate lead to the initial release of intracellular stores of calcium. This early increase of calcium induces opening of the plasma membrane calcium-released-activated-calcium (CRAC) channels,... 

The 3 isozymes are activated by G protein-coupled receptors through two different mechanisms [2]. The first involves activated a-subunits of the Gq family of heterotrimeric G proteins (Gq, Gn, Gi4, G15/16). These subunits activate the (31, (33 and (34 PLC isozymes through direct interaction with a sequence in the C terminus. The domain on the Gqa-subunit that interacts with the (3 isozymes is located on a surface a-helix that is adjacent to the Switch III region, which undergoes a marked conformational change during activation. The second mechanism of G protein activation of PLC 3 isozymes involves (3y-subunits released from Gi/0 G proteins by their pertussis toxin-sensitive activation by certain receptors. The 3y-subunits activate the 32 and 33 PLC isozymes by interacting with a sequence between the conserved X and Y domains. 

Fig. 15. Simulation of conformational changes in elongational flow by preferred rotation of bonds perpendicular to flow direction (according to Ref. [70])...

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