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19 Cards in this Set
- Front
- Back
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How do catalysts (enzyme) increase the rate of reaction? |
Lowering the activation energy (Delta G transition state) |
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What are the 3 general strategies for enzyme catalysis? |
a. enzyme binding to two substrates and encouraging a reaction between them b. Binding to a substrate and inducing a charge by rearrangement of electrons c. Enzyme strains substrate, which forces it to a transition state |
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What are cofactors? |
Either one or more essential ions required for proper function |
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What are coenzymes? |
complex organic compounds |
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Whats an apoenzyme? |
Requires a cofactor but does not have one bound therefore it is inactive |
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What is a holoenzyme? |
An apoenzyme with a prosthetic group bound, making it active
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Which model for the active site is most likely? Induced fit or lock and key? |
induced fit |
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Why are enzymes so big? |
To provide a folding framework for the active site- precisely aligns the active site residues |
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How is activation energy lowered? |
The tight binding between the enzyme and the transition state stabilizes the transition state |
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At vmax, what, in terms of the proteins, is saturated? |
All active sites saturated with substrate |
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What is the steady state assumption? |
conditions where concentration of s is >> concentration of E, so [ES] remains constant and rate of formation of [ES] are equal |
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If [S] is << Km, then.. |
the rate vo is directly proportional to [S] |
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If [S] >> Km.. |
Vo=Vmax, and the rate is maximal |
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If [S] = [Km]... |
Vo=Vmax/2 |
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What does a low Km suggest? A high one? |
Low Km= suggest that an enzyme binds to a substrate tightly High Km= enzyme binds weakly |
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What is the Michaelis-Menten Rate Equation |
V0= (Vmax*[S])/(Km+[S]) |
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what is the equation for Kcat? |
Kcat= (Vmax)/([Et]) |
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What ratio measures catalytic efficiency? |
kcat/km ratio |
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Do ALLOSTERIC enzymes obey michaelis menten kinetics? Why? |
No, results in a sigmoidal curve instead of a hyperbolic curve used to find Vmax and Km |
