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31 Cards in this Set
- Front
- Back
differences between enzyme catalyzed and uncatalyzed rxns |
1. catalysis reaches saturation 2. enzymes reduce the activation energy |
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Reaction Order |
refers to the number of molecules that need to interact |
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Vmax |
theoretical maximum velocity of the rxn |
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Km |
[S] at which half the maximal velocity is achieved. Includes the affinity of the enzyme for the substrate and the rate of conversion of ES to E+P |
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Differences between steady state and equilibrium |
1. there is only one equilibrium point (when ∆G=0) |
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steady state assumption |
[ES] is constant over time |
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Michaelis-Menton Equation |
v₀=Vmax*[S]/{Km+[S]} |
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kcat |
turnover number or catalytic constant. rate of ES→E+P. the number of reactions that an enzyme preforms per second. |
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catalytic efficiency |
kcat/Km |
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Lineweaver-burke plot |
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-1/Km |
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1/[S] |
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1/v |
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1/Vmax |
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Km/Vmax |
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Eadie-Hofstee Plot |
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Competitive Inhibitor |
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Noncompetitive Inhibitor |
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-Km |
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v0 |
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v0/[S] |
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Vmax |
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Vmax/Km |
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Factors that effect enzymes |
pH ionic strength temperature inhibitors |
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Competitive inhibtion |
inhibitor binds reversibly to the same site as the substrate Vmax is unchanged Km changes with [I]
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Mixed (noncompetitive) inhibition |
inhibitor binds both E and ES Vmax changes with [I] Km remains constant does not affect of substrate binding |
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sequential bisubstrate reaction |
both substrates first bind E then products are released. can be ordered or random. |
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ping-pong bisubstrate reaction |
the product of the first substrate is released before the second substrate binds. necessitates a modified enzyme intermediate. |
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oligomeric allosteric enzymes |
binding ligand by one subunit makes it easier for others to bind (cooperativity). these don't follow michaelis-menten; they have sigmoidal graphs. |
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the hill equation |
log[v/(Vmax-v)]=n*log[S]-logK' n=index of cooperativity=hill coefficient |
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Kd |
Measure of affinity of the ligand for the protein 1/Ka=[L][P]/[LP] |