Determination of the catalytic activity of binuclear metallohydrolases using isothermal titration calorimetry

作者：Pedroso Marcelo M; Ely Fernanda; Lonhienne Thierry^*; Gahan Lawrence R; Ollis David L; Guddat Luke W; Schenk Gerhard

来源：Journal of Biological Inorganic Chemistry, 2014, 19(3): 389-398.

DOI：10.1007/s00775-013-1079-0

• Isothermal titration calorimetry
• Kinetic assays
• Metalloenzymes
• Organophosphate-degrading enzymes

Binuclear metallohydrolases are a large and diverse family of enzymes that are involved in numerous metabolic functions. An increasing number of members find applications as drug targets or in processes such as bioremediation. It is thus essential to have an assay available that allows the rapid and reliable determination of relevant catalytic parameters (k(cat), K-m, and k(cat)/K-m). Continuous spectroscopic assays are frequently only possible by using synthetic (i.e., nonbiological) substrates that possess a suitable chromophoric marker (e.g., nitrophenol). Isothermal titration calorimetry, in contrast, affords a rapid assay independent of the chromophoric properties of the substrate-the heat associated with the hydrolytic reaction can be directly related to catalytic properties. Here, we demonstrate the efficiency of the method on several selected examples of this family of enzymes and show that, in general, the catalytic parameters obtained by isothermal titration calorimetry are in good agreement with those obtained from spectroscopic assays.

• 出版日期2014-3