Carbonic anhydrase has two substrates, carbon dioxide and bicarbonate, which are both converted to carbonic acid. Kinetic data for each is given below. Typical values for K_cat/K_m range from less than 1 mM^-1sec^-1 to as high as 2.8×10⁵ mM^-1sec^-1. What can be said about the K_cat/K_m for CO₂? Substrate K_m (mM) K_cat (sec^-1) K_cat/K_m (m M^-1sec^-1) CO₂HCO₃^- 12 26 1×10⁶ 4×10⁵ 8)3×10⁴1.5×10⁴ A) carbonic anhydrase binds CO₂ well but poorly converts it to carbonic acid B) carbonic anhydrase binds CO₂ poorly but effectively converts it to carbonic acid C) carbonic anhydrase binds CO₂ well and converts it to carbonic acid very well D) carbonic anhydrase binds CO₂ poorly and poorly converts it to carbonic acid E) the data above is useless for this question

Question

Quizplus · Accepted Answer

The $K_{cat}/K_m$ ratio is a measure of catalytic efficiency. For $CO_2$, the $K_{cat}/K_m$ is in the range of $1 \times 10^6$ to $4 \times 10^5$, indicating high efficiency both in binding ($K_m$ is low) and conversion to product ($K_{cat}$ is high). This suggests that carbonic anhydrase binds $CO_2$ well and converts it to carbonic acid very efficiently.

Carbonic Anhydrase Has Two Substrates, Carbon Dioxide and Bicarbonate, Which