5.1.1.3 L-glutamate = D-glutamate analysis of active site, mechanism 663414 5.1.1.3 L-glutamate = D-glutamate deprotonation/protonation mechanism for racemization in which the breaking of the carbon-hydrogen bond at C-2 is partially rate-determining 2116 5.1.1.3 L-glutamate = D-glutamate deprotonation/protonation mechanism. Two-base mechanism in which one enzymic base deprotonates the substrate, and the conjugate acid of a second enzymic base protonates the resulting intermediate from the opposite face 2117 5.1.1.3 L-glutamate = D-glutamate glutamate racemase faces the difficult task of deprotonating a relatively low acidicity proton, the amino acid’s R-hydrogen, with a relatively poor base, a cysteine. The titration curves and the pK1/2 values of all of the ionizable residues for different structures leading from reactants to products are analyzed. From these results a concerted mechanism is proposed in which the Cys70 residue deprotonates the R-hydrogen of the substrate while, at the same time, being deprotonated by the Asp7 residue 675616 5.1.1.3 L-glutamate = D-glutamate initial step is the proton abstraction from the substrate alpha-carbon atom, which is mediated by an amino acid residue in the enzyme protein 2120 5.1.1.3 L-glutamate = D-glutamate molecular dynamics simulations, mechanism by which binding mismatches are propagated into an opening of the active site 661155 5.1.1.3 L-glutamate = D-glutamate MurI is a member of the two-base mechanism (dual-cysteine) racemase family, where two essential active-site cysteine residues act as catalytic base and acid to stereospecifically de- and reprotonate, respectively, the alpha position of glutamate in order to enact substrate racemization -, 746766 5.1.1.3 L-glutamate = D-glutamate MurI is a member of the two-base mechanism (dual-cysteine) racemase family, where two essential active-site cysteine residues act as catalytic base and acid to stereospecifically de- and reprotonate, respectively, the alpha position of glutamate in order to enact substrate racemization. C185 of BsMurI corresponds to the essential catalytic cysteine residue that deprotonates an incoming L-glutamate substrate (or reprotonates a carbanionic intermediate to form the D-stereoconfiguration) -, 746766 5.1.1.3 L-glutamate = D-glutamate the enzyme uses a two-base mechanism in which two Cys thiolates serve as the general base/acid catalysts. An initial deprotonation event produces a resonance-stabilized carbanionic intermediate that is subsequently protonated on the opposite face to generate the enantiomeric product 2099 5.1.1.3 L-glutamate = D-glutamate the enzyme uses a two-base mechanism involving a deprotonation of the substrate at the alpha-position to form an anionic intermediate, followed by a reprotonation in the opposite stereochemical sense. Cys73 is responsible for the deprotonation of D-glutamate and Cys184 is responsible for the deprotonation of L-glutamate 650067