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In chemistry and biochemistry, the affinity constant is the reciprocal of the dissociation constant, where both are equilibrium constants describing the strength of binding between a catalyst such as an enzyme or ribozyme and its substrate. A Km value is a specific example of an affinity constant in enzymatic reactions. For example, the equilibrium for the formation of an enzyme-substrate (ES) complex between an enzyme (E) and a substrate (S),
can be represented as
where [E], [S], and [ES] are the concentrations of enzyme, substrate, and the enzyme-substrate complex, respectively, and x and y represent their stoichiometric coefficients.
The affinity constant, also known as the Michaelis constant, has units of per molar (M−1) or l/mole. Affinity constants can vary significantly with solution...
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Cleaves, H.J.(. (2015). Affinity Constant. In: Gargaud, M., et al. Encyclopedia of Astrobiology. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-662-44185-5_40
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DOI: https://doi.org/10.1007/978-3-662-44185-5_40
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