Section 22.4.3.2. CSD structures and substructures of relevance to protein studies

Table 22.4.3.1 presents statistics for the 3137 structures of amino acids and peptides that are available in the CSD of April 1998 (containing 181 309 entries). Although this represents less than 2% of CSD information, some may consider that these are the only entries of real interest in molecular biology. In certain cases, e.g. for the derivation of very precise molecular dimensions and for some conformational work, this may be true. However, the real issue concerns the transferability of CSD-derived information to the protein environment. It is the biological relevance of a chemical substructure (inter- or intramolecular) that is important, and this consideration immediately brings much larger subsets of CSD entries into play. Information such as van der Waals radii can be derived from the CSD as a whole, while more specific information concerning, for example, biologically important metal coordination geometries can be derived from appreciable subsets of the total database, as shown in the statistics of Table 22.4.3.2.