Download MendeleyA substrate-induced switch in the reaction mechanism of a thermophilic esterase: kinetic evidences and structural basis.
De Simone, G., Mandrich, L., Menchise, V., Giordano, V., Febbraio, F., Rossi, M., Pedone, C., Manco, G.(2004) J Biol Chem 279: 6815-6823
- PubMed: 14617621
- DOI: https://doi.org/10.1074/jbc.M307738200
- Primary Citation of Related Structures:
1QZ3 - PubMed Abstract:
The reaction mechanism of the esterase 2 (EST2) from Alicyclobacillus acidocaldarius was studied at the kinetic and structural level to shed light on the mechanism of activity and substrate specificity increase previously observed in its double mutant M211S/R215L. In particular, the values of kinetic constants (k1, k(-1), k2, and k3) along with activation energies (E1, E(-1), E2, and E3) were measured for wild type and mutant enzyme. The previously suggested substrate-induced switch in the reaction mechanism from kcat=k3 with a short acyl chain substrate (p-nitrophenyl hexanoate) to kcat=k2 with a long acyl chain substrate (p-nitrophenyl dodecanoate) was validated. The inhibition afforded by an irreversible inhibitor (1-hexadecanesulfonyl chloride), structurally related to p-nitrophenyl dodecanoate, was studied by kinetic analysis. Moreover the three-dimensional structure of the double mutant bound to this inhibitor was determined, providing essential information on the enzyme mechanism. In fact, structural analysis explained the observed substrate-induced switch because of an inversion in the binding mode of the long acyl chain derivatives with respect to the acyl- and alcohol-binding sites.
Organizational Affiliation:
Istituto di Biostrutture e Bioimmagini-Consiglio Nazionale delle Ricerche, via Mezzocannone 6, 80134 Naples, Italy.
