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4 Cards in this Set
- Front
- Back
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Define the Michaelis-Menten equation |
Vo=Vmax[S]/ Km+[S] The equation represents the relationship between [S] and Vmax. It has a general shape for most enzymes (rectangular hyperbola). In this equation, the [S] is much greater than the concentration of enzyme, the reaction has a steady state intermediate, and only the initial reaction rates are taken into consideration. An increase in substrate concentration means an increased reaction rate up to a point where all enzymes are saturated=Vmax Hyperbolic curve Km =enzymes efficiency of affinity to bind substrate (lower Km= more affinity) |
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Know the effects of substrate concentration, temperature, and pH on enzyme reaction rates |
--pH: each enzyme has an optimal pH for which it works. When used at any other pH, the reaction rate is negatively affected. --substrate concentration: when the [enzyme] is constant, the reaction rate will increase as the amount of [substrate] is increased. Eventually though, the reaction rate levels off= Vmax aka the maximum velocity of rxn. --As temperature is increased, the rxn rate of an enzyme increases. Molecules have more collisions and energy is increased. However, there is an optimal temperature, and beyond that the rxn rate decreases. This occurs because enzymes will denature at certain temps. |
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Define Vmax, Km, kcat, and Keq |
--Vmax: the maximum velocity of an enzyme reaction when the binding site is saturated with substrate. --Km: the Michaelis constant. Km=[S] when Vo= 1/2 Vmax. --Kcat: a first order rate constant of a rxn. In a reaction with several steps, kcat is the equivalent to the rate constant of the limiting step of that reaction. Kcat=Vmax/[Et] --Keq: equilibrium constant: characteristic for each chemical reaction, relates the specific concentrations of all reactants and products at equilibrium at a given temp and pressure. |
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Contrast Michaelis-Menten and Lineweaver-Burk plots |
The Linweaver-Burk plot is dimly the reciprocal of the Michaelis-Menten equation: 1/Vo= 1/Vmax + Km/Vmax (1/[S]) In addition, the Lineweaver-Burk plot results in a straight line graph, which is easier to determine Vmax and Km values than the hyperbolic curve of the Michaelis-Menten plot, which results in estimation of the Vmax value. |
