Maximum common substructure MCS

A key concept in the assessment of molecular similarity based on chemical graphs is that of a maximum common substructure, MCS(G,GJ), of two chem-... 

Fig. 1. An example of two hydrogen-suppressed graphs G1 G2 and a common substructure CSIG,, G2) and the maximum common substructure MCS(G1 G2) are shown above. The Tanimoto similarity index and the distance between the two chemical graphs are computed below.

In general, the term scaffold is applied in a multimde of ways to describe a molecular core structure, for example, as a common element of a chemical series or for building blocks in synthetic chemistry. For closely related compounds, such a scaffold could be defined by their maximum common substructure (MCS) [22]. 

FIGURE 153 Example of a chemical graph-based ealculation of molecular similarity, (a) Chemical graph of acetylcholine, (b) Chemical graph of an acetylcholine analog, (c) A common structure (CS) of (a) and (b). (d) The maximum common substructure (MCS) of... 

Figure 17 Cluster analysis of 44 isomers with molecular formula C6H3CI3 by principal component analysis (score plot of the first and second principal component containing 41.2% and 18.8% of the total variance, respectively). The chemical structures have been characterized by 20 binary molecular descriptors. The common structural properties within each cluster are characterized by the maximum common substructure (MCS). [Reproduced from Ref. 133 with kind permission of Gesellschaft Deutscher Chemiker]...

---