Ligand structural index

Information may be stored in the architecture of the receptor, in its binding sites and in the ligand layer surrounding bound <7 it is read out at the rate of formation and dissociation of the supermolecule. In addition to size and shape, a receptor is characterized by the dimensionality, the connectivity and the cyclic order of its structural graph these features have been used to define a ligand structural index L ... 

These databases are a rich source of information, yet they do not capture an element of interest, namely the biological endpoint there is no searchable field to identify, in a quantitative manner, what is the target-related activity of a particular compound. Such information is important if one considers that (a) not all chemotypes indexed in patent databases are indeed active - some are just patent claims with no factual basis and that (b) not aU chemotypes disclosed as active are equally active, or selective for that matter, on the target of choice. Furthermore, should one decide to pursue a certain interaction hotspot in a given ligand-receptor structure (assuming good structure-activity models are available), it would be very convenient to mine structure-activity databases for similar chemotypes to use as potential bioisosteric replacements. 

The structures in Figures 2-6 illustrate the utility of a ligand index-based stereochemical notation for coordination compounds. 

Special attention is also given to the description of names of metal-cyclic structures [28]. If a group of simultaneously coordinated atoms of the chelating ligand is present in the complex, the symbols of all atoms and groups are enumerated, separated by a comma, after the symbol Q followed by a An upper index number on the right of the symbol of an element indicates its number within the group. 

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