How protein and medium engineering affect thermodynamic drive of enzymatic processes

Abstract Here, techniques used to manipulate enzyme activity and selectivity are discussed. Modifications employed in protein structural changes and medium engineering directly influence the mode of enzyme-substrate interactions, with those having the lowest binding energies most preferred. Substrates and product selectivity depend on solvation/desolvation and steric effects at the active site of the enzyme. Single, double and triple site-directed mutagenesis and the use of multiple enzymes have been employed to achieve the desired selectivity. The thermodynamic favorability of enzyme-catalysed processes is observed as enhanced activity/stereoselectivity, and it relies on all the key intermediates/transition states. Entropy contributions override the contribution of the process enthalpies. Besides protein and medium engineering, enzyme activity and selectivity are also manipulated by support systems such as metal ions, metal organic frameworks, silica and cofactors/coenzymes, which influence substrate orientations and binding energies. Binding energies depend on substrate structure, size and poses assumed at the active site, and the number of enzyme receptor and substrate binding sites. Wild-type enzymes can switch the thermodynamically favoured pathway, leading to selectivity mistakes and low enantiomeric excess. In general, selectivity is thermodynamically driven while activity depends on reaction kinetics.