The CATH wheel for KEGG pathways. The color of the CATH wheel represents the CATH classes, where yellow stands for alpha/beta, red for mainly alpha, blue for mainly beta, and green for Few Secondary Structures. The inner circle represents the CATH architectures (C.A.), where the width of each segment represents the number of enzymes found to exhibit that architecture. The outer circle stands for the Topology (C.A.T.). (A) shows the distribution of all enzymes participating in KEGG pathways with the '3-layer(aba) sandwich' representing the largest architecture. (B) shows the CATH wheel for the pathway 'Pyrimidine metabolism' while (C) for 'Glycolysis/Gluconeogenesis'.