Km is substrate concentration at half Vmax in Michaelis-Menten kinetics

Steps:

• Identify Vmax as maximum reaction rate from the graph's asymptote.
• Locate half Vmax on the y-axis (rate axis).
• Find substrate concentrations [S] where rate equals Vmax (one point) and half Vmax (another point).
• Km equals [S] at half Vmax; use paired points for interpolation if needed.

Why C is correct:

• K and L represent substrate concentrations at Vmax and half Vmax, allowing direct calculation of Km as [S] at half Vmax per Michaelis-Menten equation.

Why the others are wrong:

• A: J and K likely both on low-rate side, not spanning half Vmax.
• B: J and M mix initial rate and high [S], irrelevant to half Vmax.
• D: L and M both on high-rate side, exceeding half Vmax without Vmax reference.

Final answer: C