Definition of Michaelis constant in US English:

Michaelis constant


  • The concentration of a given enzyme that catalyzes the associated reaction at half the maximum rate.

    • ‘This result is different from the previous one where at least two sets of Michaelis constants were needed to fit the hydrolysis kinetics.’
    • ‘Although this residue appears to be absolutely conserved, its replacement by the less bulky alanine or the more bulky cystein has relatively little influence on the catalytic rate and the Michaelis constant of the enzyme.’
    • ‘Historically, it was observed that selenate and sulphate competed for influx to roots, and exhibited similar Michaelis constants for high-affinity transport.’
    • ‘In such a model, the locus q controls the activity of enzyme q, and qi depends on the maximal velocity and on the Michaelis constant of enzyme q in individual i.’
    • ‘The JHEs did not differ in any biochemical characteristic such as Michaelis constant, inhibition, or thermostability.’


1930s: named after Leonor Michaelis (1875–1949), German-born American chemist.


Michaelis constant

/məˈkālis ˌkänst(ə)nt/