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Catalytic efficiency and kcat/KM: a useful comparator?

2007; Elsevier BV; Volume: 25; Issue: 6 Linguagem: Inglês

10.1016/j.tibtech.2007.03.010

0167-9430

Robert Eisenthal, Michael J. Danson, David W. Hough,

Protein Structure and Dynamics

The ratio kcat/KM – often referred to as the 'specificity constant' – is a useful index for comparing the relative rates of an enzyme acting on alternative, competing substrates. However, an alternative description, 'catalytic efficiency', is frequently used, and on occasions misused, to compare the reactivity of two enzymes acting on the same substrate. Here, we highlight the pitfalls in using kcat/KM to compare the catalytic effectiveness of enzymes. The ratio kcat/KM – often referred to as the 'specificity constant' – is a useful index for comparing the relative rates of an enzyme acting on alternative, competing substrates. However, an alternative description, 'catalytic efficiency', is frequently used, and on occasions misused, to compare the reactivity of two enzymes acting on the same substrate. Here, we highlight the pitfalls in using kcat/KM to compare the catalytic effectiveness of enzymes. Efficiency function for comparing catalytic competenceCeccarelli et al.Trends in BiotechnologyMarch, 2008In BriefThe article by Eisenthal et al. in the June issue of Trends in Biotechnology [1] warns on the use and misuse of kcat/KM (the 'specificity constant' [2]) for evaluating the performance of enzymes. We endorse these concepts, and along the same lines we propose an alternative formulation that enables estimation of true enzyme-catalyzed reaction efficiencies with practical applications. Our approach overcomes many of the pitfalls of using kcat/KM values and is powerful in predicting the efficiency of enzyme variants in reactors or when expressed in transgenic organisms. Full-Text PDF