Scientists could confirm that an allosteric effector increases the catalytic efficiency of an enzyme if it has what effect on k_cat and K_m?

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11ecba2d_0e5f_6482_a3bf_ab6e53b39b82_MD0008_00 Catalytic efficiency is a measure of how well an enzyme facilitates reactions at low substrate concentrations. When enzyme concentration is held constant, catalytic efficiency is proportional to the initial slope of a Michaelis-Menten curve (when [S] << K_m). This slope is governed by both the catalytic turnover k_cat and the Michaelis constant K_m. Mathematically, catalytic efficiency is calculated as the ratio of k_cat to K_m. An increase in k_cat increases the catalytic efficiency, and a decrease in K_m also increases the efficiency. Therefore, an allosteric activator that both increases k_cat and decreases K_m will increase the catalytic efficiency of an enzyme. Conceptually, a large (steep) slope indicates an efficient enzyme because a small amount of substrate yields a high reaction rate. Catalytic turnover (k_cat) measures the number of substrate molecules converted to product per enzyme per second when the enzyme is saturated; therefore, a high k_cat corresponds to a high maximum rate (V_max) and, by extension, a larger slope at lower substrate concentrations. The Michaelis constant (K_m) is an indicator of binding affinity. A small K_m indicates high affinity, allowing the reaction to approach V_max more rapidly (higher slope) with smaller amounts of substrate. Therefore, a small K_m contributes to high catalytic efficiency. (Choice A) A decrease in k_cat and an increase in K_m would decrease catalytic efficiency. (Choice B) If K_m is unchanged, a decrease in k_cat will cause a decrease in catalytic efficiency. A decrease in k_cat must be overcome by a proportionally greater decrease in K_m for catalytic efficiency to increase. (Choice D) If k_cat is unchanged, an increase in K_m will decrease catalytic efficiency. An increase in K_m must be overcome by a proportionally greater increase in k_cat for catalytic efficiency to increase. Educational objective: Catalytic efficiency is a measure of an enzyme's ability to catalyze reactions at low substrate concentrations. Efficiency is calculated as k_cat/K_m, and its value can be increased by increasing k_cat or by decreasing K_m.

Scientists Could Confirm That an Allosteric Effector Increases the Catalytic