Title: Michaelis–Menten equation
Long Title: IUPAC Gold Book - Michaelis–Menten equation
DOI: 10.1351/goldbook.11546
Status: current

Definition
The relationship between the initial rate (velocity) of an enzyme-catalysed reaction \(v_{0}\) and the initial substrate concentration \([\ce{S}]_{0}\) in the form \[v_{0} = V[\ce{S}]_{0}/(K_{\rm{M}} + [\ce{S}]_{0})\] where \(V\) (the limiting rate) and \(K_{\rm{M}}\) (the Michaelis constant) are independent of the initial substrate concentration and constant at a given temperature and a given enzyme concentration. The reaction is then said to display Michaelis–Menten kinetics.

Notes
1) The term ‘hyperbolic kinetics’ is also sometimes used, because a plot of \(v_{0}\) against \([\ce{S}]_{0}\) has the form of a rectangular hyperbola through the origin with asymptotes \(v_{0} = V\) and \([\ce{S}]_{0} = -K_{\rm{M}}\). This term, and others that imply the use of particular kinds of plot, should be used with care to avoid ambiguity, as they can be misleading if used out of context.
2) The symbol \(V_{\rm{max}}\) and the names "maximum rate" and "maximum velocity" are also in widespread use, although in general and under normal circumstances there is no finite substrate concentration at which \(v_{0} = V\). Hence, there is no maximum in the mathematical sense. The alternative name Michaelis concentration for \(K_{\rm{M}}\) may also be used and has the advantage of emphasizing that the quantity concerned has the dimension of a concentration and is not, in general, an equilibrium constant. The Michaelis constant is the substrate concentration at which \(v_{0} = V/2\).

Source
- PAC, 2018, 90, 1121. 'Terminology of bioanalytical methods (IUPAC Recommendations 2018)' on page 1134 (https://doi.org/10.1515/pac-2016-1120)

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Citation: Citation: 'Michaelis–Menten equation' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.11546
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Accessed: 2026-08-04T04:07:45+00:00