Given the enormous biomedical importance of screening inhibitor of the metallo-beta-lactamases (M beta Ls), we determined the thermokinetic parameters of cefalexin hydrolysis with M beta LL1 from Stenotrophomonas maltophilia in the absence and presence of 2,5-pyrrolidinedicarboxylic acid (PDA) as enzyme inhibitor. The presence of PDA caused a value decrease of the rate constant k, and a value increase of the apparent activation energy E (from 33.88 to 35.46 kJ mol(-1)), activation enthalpy Delta H-not equal(theta) (from 31.35 to 32.92 kJ mol(-1)), activation free energy Delta G(not equal)(theta) and activation entropy Delta S-not equal(theta) (from -201.31 to -196.39J mol(-1) K-1) in comparison with the absence of PDA in the temperature range of 298.15-313.15K, proposing that the changes of k, E, Delta H-not equal(theta) and Delta S-not equal(theta) values can be employed to identify the inhibitors of M beta Ls. (C) 2013 Elsevier B.V. All rights reserved.