Ethan's Notes

    Mixed Inhibition

    #Biochemistry
    Inhibitor binds allosterically to either the enzyme or ES complex. We define $\displaystyle K_{I}$ to be the dissociation constant for the free $\displaystyle \ce{EI}$ complex (equilibrium constant for converting $\displaystyle \ce{EI->E + I}$) and $\displaystyle K_{I}'$ to be dissociation constant for the $\displaystyle \ce{ESI}$ complex
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    • $\displaystyle K_{m}$ increased if $\displaystyle K_{I}<K_{I}'$ where $\displaystyle K_{m}$ is the Michaelis constant
      • If the inhibitor binds more strongly to E than it does to ES, binding affinity of E to S decreases, so $\displaystyle K_{m}$ increases
      • This is kind of analogous to competitive inhibition since for lower relative $\displaystyle K_{I}$, we'll have less free $\displaystyle E$, which is kind of how the competitive inhibitor takes away free $\displaystyle E$. Competitive inhibition also increases $\displaystyle Km$
    • $\displaystyle K_{m}$ decreased if $\displaystyle K_{I}>K_{I}'$
      • If the inhibitor binds more strongly to ES than it does to E, binding affinity of E to S increases, so $\displaystyle K_{m}$ decreases
    • $\displaystyle v_{\text{max}}$ decreased due to general inhibition
    • Desmos Graph of Lineweaver-Burk Plot for Mixed Inhibition

    Lineweaver-Burk Plot

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