Kinetic modelling of coupled redox enzymatic systems for in situ regeneration of NADPH

In the past few years, we have been working in a complete comparative kinetic study involving three different NADPH recycling reactions having the reduction of 6-methyl-5-hepten-2-one (sulcatone) catalysed by alcohol dehydrogenase from Thermoanaerobium brockii (TBADH) and producing S-(+)-6-methyl-5-hepten-2-ol (sulcatol) as the main reaction. A fundamental step in this study involves the elucidation of the kinetic mechanism of the main reaction, which must be the rate-limiting step of the overall process in all systems studied. In the present work, we demonstrated by initial velocity and product inhibition studies that sulcatone/sulcatol reduction reaction follows a Theorell–Chance BiBi mechanism. Using the kinetic parameters hereby and previous determined, it was possible to simulate time-course curves for coupled enzymatic systems used. Considering the good correlation between the adjusted curves and experimental data it is possible to affirm that coupled enzymatic reaction systems can be kinetically described by evaluating just the kinetic behaviour of the main reaction.