Corroborative models

Before plunging into a discussion of how such complexes are prepared, it is perhaps worthwhile to consider explicitly the rationale for such activity. The synthesis and characterization of accurate model complexes for a given metal site in a protein or other macromolecule allows one to (l) determine the intrinsic properties of the metal site in the absence of perturbations provided by the protein environment or (il) in favorable cases, deduce the structure of the metal site by comparison of corresponding physical and spectroscopic properties of the model and metalloprotein (3). The first class of model complexes has been termed "corroborative models" by Hill (4), while the second are termed "speculative models" (4). To date, virtually all the major achievements of the synthetic model approach have been in development of corroborative models. 

A set of molecules that rank high after this process would be synthesized and subject to biological tests, i.e., in vitro enzymatic assay or binding affinity experiments, in order to confirm design rationales. Simultaneously, X-ray co-crystal structures of these ligands in complex with the target are to be determined to further corroborate modeling results. Positive results from such approaches are decisive for selection of next set of compounds for synthesis and the future directions of lead optimization. 

Hill introduced two useful definitions for model compounds of metalloproteins, — speculative models and corroborative models, Speculative models are prepared when the structure of the microenvironment of the metallobiosite is unknown and the objective is to reproduce some physico-chemical property of the system in a small molecule complex. When the structure of the metallobiosite is known a corroborative model can be prepared. This is usually a small molecule complex in which the environment of the metal is reproduced as accurately as possible. It then becomes possible to determine whether the observed properties of the metal in the protein are dominated by the first coordination sphere and can give insights into the relationship between structural features of the metallobiosite and its physical properties. 

Several results are quite apparent from the data shown in Table II. It is evident from the pentapeptide model compounds that substitution of amino acid residues at positions 4 and 5 does not significantly affect the structure about the N-terminus. This observation corroborated earlier work from agglutination-inhibition assays, which demonstrated that the nature of the amino acid at position 4 of the peptide (or glycopeptide) is not a requirement for specificity. 

At this stage, it is difficult to determine what role direct and indirect neurotoxicity plays in DSP. Further in vivo studies are needed to corroborate the in vitro studies. What is needed is a reliable animal model of HIV infection that also shows PNS neurotoxicity (Hoke and Comblath 2004). 

A possible explanation for the difference in tendencies of the deposition rate between experiment and model is that in the model the surface reaction and sticking coefficients of the radicals are taken to be independent of the discharge characteristics. In fact, these surface reaction coefficients may be influenced by the ions impinging on the surface [251]. An impinging ion may create an active site (or dangling bond) at the surface, which enhances the sticking coefficient. Recent experiments by Hamers et al. [163] corroborate this the ion flux increases with the RF frequency. However, Sansonnens et al. [252] show that the increase of deposition rate cannot be explained by the influence of ions only. 

The aim of this contribution is to provide a molecular insight through density functional theory modeling corroborated with spectroscopic investigations (both in static and flow regimes) into the binding and activation of nitrogen oxides on various TMIs of different... 

Perhaps the most extensive computational study of the kinetics of NO reactions on Rh and Pd surfaces has been provided by the group of Zgrablich. Their initial simulations of the NO + CO reaction on Rh(lll) corroborated the fact that the formation of N-NO intermediate is necessary for molecular nitrogen production [83], They also concluded that an Eley-Rideal mechanism is necessary to sustain a steady-state catalytic regime. Further simulations based on a lattice-gas model tested the role of the formation of... 

Son and Hanratty (S19) reviewed the experimental evidence from electrochemical and other model experiments. They concluded that eddy diffusivity varies with the fourth power of the distance from the wall, assuming that the friction factor takes care of the Reynolds number dependence. Shaw and Hanratty (SIla) recently corroborated this conclusion by further experiments that led to the equation (47b, (5)) in Table VII, which is equivalent to... 

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