5.1.1.4	L-proline = D-proline	racemization is accompanied by deuterium incorporation from the solvent into the alpha position of Pro, participation of two equivalent hydrogen acceptor sites	2121	
5.1.1.4	L-proline = D-proline	two-base mechanism in which one base on the enzyme removes the substrate alpha-hydrogen as a proton and the conjugate acid of another base donates a proton to the opposite side of the alpha-carbon	2124	
5.1.1.4	L-proline = D-proline	mechanism	2125	
5.1.1.4	L-proline = D-proline	energetics of proline racemase: transition-state fractionation factors for the two protons involved in the catalytic steps	2126	
5.1.1.4	L-proline = D-proline	stepwise reaction for the interconversion of the free enzyme forms in which a proton is abstracted from a bound water molecule to give a reaction intermediate having a hydroxide ion bound to the diprotonated form of the enzyme	2127	
5.1.1.4	L-proline = D-proline	enzyme exists in two states, one of which binds and isomerizes L-Pro and the other of which binds and isomerizes D-Pro. It seems likely that the two enzyme forms differ only in the protonation states of the acidic and basic groups at the active site	2128	
5.1.1.4	L-proline = D-proline	fractionation factors for the essential catalytic groups in the enzyme-substrate complexes	2129	
5.1.1.4	L-proline = D-proline	mechanism is best accomodated by a route that involves a transition state or unstable intermediate in which the proline carbanion is flanked by the two catalytic thiols of the enzyme	2130	
5.1.1.4	L-proline = D-proline	the substrate and product "on-off" steps are faster than the racemization step and the racemization reaction proceeds either in a concerted manner or in a stepwise fashion involving enzyme catalytic groups, e.g. thiols	2131	
5.1.1.4	L-proline = D-proline	a new combined quantum mechanical and molecular mechanical (QM/MM) potential to study the reaction mechanism of proline racemase is used. Three critical points are identified: two almost isoenergetic minima (M1a and M2a), in which the enzyme is bound to L- and D-Pro, respectively, and a transition state (TSCa), unveiling a highly asynchronous concerted process	675621