Enzyme Kinetics Flashcards
What is 1 international unit of enzyme activity?
The amount of enzyme it takes to catalyse the transformation of 1umol of substrate/min at 25c under optimal conditions of substrate and pH of that enzyme
What is enzyme activity usually measured in?
umol/min/L or umol/min/g
What do catalysts do?
- Increases the rate of reaction via lowering activation energy
- Facilitates formation of the transition state and stabilises it
- Does not effect reaction equilibrium
What type of curve is rate of reaction usually?
-Hyperbola
What is the rate of reaction proportional to?
-Enzyme concentration
What is Vo?
-Rate of reaction
What effect does an inhibitor have on Vo?
-Decreases it
What information can you derive from a Lineweaver Burk plot?
- 1/Vmax from the Y-intercept
- 1/km from the x-intercept
What are the axis in a lineweaver burk plot?
- 1/[S] on x-axis
- 1/V on y-axis
Why are some inhibitors irreversible?
-They are covalently linked to the enzyme
What are the two types on reversible inhibitor?
- Competitive
- Non-competitive
How do competitive inhibitors work?
-Resemble the substrate and bind to the active site
What effect do competitive inhibitors have on enzyme kinetics?
- No effect on Vmax
- Increases the Km of the enzyme for the substrate as it competes with the substrate for the active sites of the enzyme. Therefore it takes more substrate to overcome the inhibitor and reach 1/2Vmax
How do non-competitive inhibitors function?
- Binds to another site than the active site
- Either alters the shape of the active site
- Or stops release of ES complex
What effect do non-competitive inhibitors have on enzyme kinetics?
- Km is unaffected
- Vmax is reduced as there is decreased turnover of enzyme->substrate
