Updated: 12/11/2021

# Enzyme Kinetics

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 Overview Kinetic theory for two molecules to react they must be within bond-forming distance possess enough kinetic energy to overcome the activation energy (Ea) factors that affect these two conditions will either decrease or increase the reaction rate temperature: causes an increase in kinetic energy concentration of reactants: increases probability of collisions Gibbs free energy change (ΔG)  is the free energy change between the products and the reactants reflects the direction of a reaction and amount of reactants and products at equilibrium, but does NOT determine the rates of reaction ΔG < 0: reaction is spontaneous and favors product formation ΔG = 0: reaction is at equilibrium and proceeds in both direction at equal rates ΔG > 0: reaction is nonspontaneous and favors reactant formation Ea determines the rate of the reaction a large Ea will have a slower rate a small Ea will have a faster rate enzymes lower the Ea allowing the reaction to proceed at a faster rate enzymes do NOT change the ΔG of the reaction just the Ea enzymes are sensitive to temperature and pH Enzymes Kinetics Michaelis-Menten Equation   an equation that relates the initial reaction velocity (Vi) to the substrate concentration Vmax is directly proportional to the [E]  Km is the Michaelis-Menten constant which represents the substrate concentration at which Vi is half the maximum velocity (Vmax) Km = [S] at 1/2 Vmax Km is related to the enzyme's affinity for the substrate [S] ↑ Km = ↓ affinity ↓ Km = ↑ affinity inhibitors affect these enzyme parameters competitive increases Km noncompetitive decreases Vmax Lineweaver-Burk Equation an inverted form of the Michaelis-Menten equation used to calculate Vmax and Km from experimental data at below enzyme saturation levels the equation is in the format y = ax + b (a is the slope and b is the y intercept) y = 1/Vi x = 1/[S] a = Km/Vmax b = 1/Vmax helpful hints the smaller value of -1/Km, the greater the Km ↑ y-intercept = ↓ Vmax

Average 3.8 of 9 Ratings

Questions (3) Sorry, this question is for Sorry, this question is for

(M1.PH.14.23) In your peripheral tissues and lungs, carbonic anhydrase works to control the equilibrium between carbon dioxide and carbonic acid in order to maintain proper blood pH. Through which mechanism does carbonic anhydrase exert its influence on reaction kinetics?

QID: 100088
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Lowers the activation energy

59%

(174/295)

2

Changes the delta G of the reaction

11%

(32/295)

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Raises the activation energy

11%

(31/295)

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Lowers the free energy of products

6%

(17/295)

5

Lowers the free energy of reactants

9%

(26/295)

M 1 E

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