Virtual topologies

Virtual Topologies The practice of using an application topology on a machine with a different true topology (e.g., mapping a ring to a hypercube or mesh). 

Several research groups have built models using theoretical desaiptors calculated only from the molecular structure. This approach has been proven to be particularly successful for the prediction of solubility without the need for descriptors of experimental data. Thus, it is also suitable for virtual data screening and library design. The descriptors include 2D (two-dimensional, or topological) descriptors, and 3D (three-dimensional, or geometric) descriptors, as well as electronic descriptors. 

Observation 1 Since primitive graph decompositions are not particularly representative of global topologies, it can hardly be surprising to find a large number of nonisomorphic topologies supporting virtually the same dynamics. 

RP and 71.7% ANN. The key descriptors for the RP model are 12 topological indices that include six E-state indices, i.e. SssCH2, SssO, SaasC, SdO, SsssN and SssssC. The classifier that combines topological indices and decision trees may be used for the virtual screening of DA, SA and Dual antagonists. 

Schneider, G., Neidhart, W., Giller, T., and Schmidt, G. Scaffold-Hopping by topological pharmacophore search a contribution to virtual screening. Angeiv. Chemie. 1999, 111, 3068-3070. 

HertJ, Willett P, Wilton D, etal. (2004) Topological descriptors for similarity-based virtual screening using multiple bioactive reference structures. Org. Biomol. Chem. 2 3256-3266. 

Schneider G, Neidhart W, Giller T, Schmid G. (1999) Scaffold-hopping by topological pharmacophore search A contribution to virtual screening. Angew. Chem. Int. Ed. Engl. 38 2894—2896. 

The virtual library was then characterized using the Cerius2 default topological descriptors and physicochemical properties (35). The 50 default descriptors were reduced to three principal components using principal components analysis, and this defined a 3D chemistry space into which the virtual library could be plotted. The chemistry space consisted of 1134 cells and, when the virtual library was mapped into the space, it was found to occupy 364 of the cells thus, this represents the maximum cell coverage that is achievable. 

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