The sequence identity and Euclidean distance of enzymes with the same and different mechanism. The diagram presents, for every pair of proteins in the mechanism + negative datasets, the percentage of identity between the two proteins’ sequences and also the Euclidean distance between their signature sets (in the InterPro attribute space). Protein couples having the same MACiE mechanism are represented as circles, while those with different MACiE mechanisms as triangles. The colour scale is logarithmic increasing from blue (for one instance) to light blue (2-3 instances), green (4-9), yellow (70-100), orange (250) and red (up to 433 instances) and represents the number of protein couples having that sequence identity and Euclidean distance. The dashed grey line shown, with equation Euclidean distance = 7 × sequence identity, separates most same-mechanism couples (on its right) from an area dense with different-mechanism couples on its left.