Michaelis Constant

$K_m=\frac{k_{-1}+k_2}{k_1}$

• Parameter in the Michaelis-Menten equation that correlates with how quickly an enzyme reaches $v_{\text{max}}$ when increasing $[S]$. Lower $K_m$ means higher enzyme binding affinity for the substrate
• Actual definition is the $[S]$ at which $\frac{v_{\text{max}}}{2}$ is reached
• Can also be thought of as how much $\mathrm{ES}$ tends to dissociate
• $k_{-1}+k_2$ corresponds to the efflux of ES into E + S and E + P whereas $k_1$ corresponds to the influx from E + S to form ES