enzyme kinetics (class 12) Flashcards
Enzyme Kinetics is…
the study of the rates at which enzymes catalyze reactions
Vmax
maximal velocity (rate) of catalysis. Occurs when enzyme is saturated
Km
- Michaelis menten constant
-Km= concentration of S when rate is 1/2 Vmax.
What does a low Km mean?
High affinity for substrate.
Kcat
(turnover number) expresses the rate at which substrate molecules
are converted to product by a single enzyme molecule when the enzyme is operating at its maximum velocity; varies greatly among different
enzymes
efficiency equation
Kcat/Km
Initial Velocity Assumption
reaction reaches steady state very quickly so the initial rate of the reaction is an accurate measurement of reaction rate, [P] is negligible
Michaelis-Menten Equation
V0= Vmax (S)/ Km+ (S)
Competitive inhibition
- binds directly to active site
What happens to Vmax and Km in competitive inhibition?
- requires more substrate to reach Vmax
- Vmax same, but Km changes (Km apparent is higher, indicating lower affinity
to substrate)
Noncompetitive Inhibition
Binding Site: The inhibitor can bind to either the free enzyme or the enzyme-substrate complex.
What happens to Vmax and Km in competitive inhibition?
The maximum reaction rate (Vmax) decreases, but the Michaelis constant (Km) remains unchanged. This is because the inhibitor affects the enzyme’s activity regardless of whether the substrate is bound.
Lineweaver Burk Plot
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