Fig 1.
Survey of EC numbers associated with more than one enzyme reaction.
(a) Overall distribution. Coloured slices indicate single and multi-reaction EC numbers. “R-group” represents EC numbers containing a Markush label in at least one reaction (see Generic reactions in main text) (b) Distribution by EC class (c) Distribution of EC numbers according to the number of reactions.
Fig 2.
Examples of isomerase EC numbers associated with more than one enzyme reaction.
(a) A schematic diagram summarising the groups of reaction diversity. (b) Arginine racemase (EC 5.1.1.9) is an isomerase acting on different reactants. The variability in chemical substituents is highlighted in green and the common scaffold in black. (c) Amino acid racemase (EC 5.1.1.10) is an example of generic reaction on the basis of R-group. Same colouring as in (b). (d) 2-acetolactate mutase (EC 5.4.99.3) is an example of generic reaction based on stereochemistry. The stereochemistry of C2 in acetolactate is represented as straight (undefined), up and down (defined) bonds and highlighted in green. (e) UDP-N-acetyl-D-glucosamine 2-epimerase (EC 5.1.3.14) belongs to partial reaction, (i) overall reaction–epimerisation of UDP-N-acetyl-α-D-glucosamine (green) and UDP-N-acetyl-α-D-mannosamine (blue), (ii) first partial reaction–hydrolysis and epimerisation of UDP-N-acetyl-α-D-glucosamine and (iii) second partial reaction–addition of UDP to N-acetyl-α-D-mannosamine. Intermediate compounds are highlighted in red. (f) Dichloromuconate cycloisomerase (EC 5.5.1.11) and 4-chlorobenzoyl-CoA dehalogenase (EC 3.8.1.7) catalyse different types of reactions. Shared bond changes are coloured in black, whereas different bond changes in green.
Fig 3.
An overview of reaction diversity in the EC classification.
(a) Frequency of reaction diversity group assignments. (b) Total number of multi-reaction EC numbers by EC class for each group of reaction diversity. The colour code is identical to Fig 2A.
Fig 4.
Examples of the collective and specific approaches.
(a) The different reactants of arginine racemase (EC 5.1.1.9) are combined into a single-reaction EC number using R-group. (b) The two different types of reaction catalysed by 4-chlorobenzoyl-CoA dehalogenase (EC 3.8.1.7) are split and re-defined into two single-reaction EC numbers.