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. 2016 Feb 3;11(2):e0147952. doi: 10.1371/journal.pone.0147952

Fig 2. Examples of isomerase EC numbers associated with more than one enzyme reaction.

Fig 2

(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.