3.3.2.13	evolution	three subfamilies of chorismatases are described that convert chorismate into different (dihydro-)benzoate derivatives (CH-FkbO, CH-Hyg5, and CH-XanB2). The CH-FkbO and CH-Hyg5 subfamilies share the same protein fold, but employ fundamentally different reaction mechanisms, comparisons of the reaction mechanism of CH-FkbO and CH-Hyg5 and structure-function analysis, overview	748026	
3.3.2.13	additional information	analysis of catalytic mechanisms of chorismatases EC 3.3.2.13 and EC 4.1.3.45 by molecular dynamics simulations and hybrid quantum mechanical/molecular mechanical (QM/MM) calculations of the Michaelis complexes of two wild-type models (FkbO and Hyg5) and four mutant models with chorismate as substrate, comparison of the catalytic mechanisms between FkbO and Hyg5, overview. The A/G residue group (A244FkbO/G240Hyg5) causes changes in the binding states of the substrate and the orientation of the catalytic glutamate, but only these changes affect the product selectivity in chorismatases limitedly. The distal V/Q residue group, which determines the internal water self-regulating ability at the active site, has significant impact on the selectivity of the catalytic mechanisms. The V/Q residue group is suggested to be an important factor to control the catalytic activities in chorismatases	753274	
3.3.2.13	additional information	structure of Fkbo-substrate complex, the solvated model of CH-Fkbo is optimized to calculate the catalytic mechanism. In the reactant structure, the substrate chorismate takes the similar binding model as inhibitor 3-(2-carboxyethyl)benzoate in crystal structure and adopts a trans-pseudodiaxial conformation. The structure of Streptomyces hygroscopicus chorismatase CH-Hyg5 is very similar to that of Streptomyces hygroscopicus chorismatase CH-Fkbo, all amino acid residues in the active site are the same except residues G240Hyg5 (A244Fkb8) and C327Hyg5 (A331Fkb8) are the same. The optimized active site structure of Hyg5 complex is superpositioned with that of Fkbo, overview. Two nonconserved active site residues are responsible for the different reaction mechanism of CH-Fkbo and CH-Hyg5. In CH-Hyg5, the lack of methyl in G240Hyg5 leads to the different conformation of the side chain of E334 (or E338) in Hyg5 and Fkbo. This small change eventually decreases the ESP charge of C3 atom of the substrate, which facilitates the cleavage of C3-O8 bond in Hyg5. Furthermore, C327Hyg5 is involved in the selective product formation in Hyg5 enzyme	755348