Flashcards
Enzyme kinetics
Flashcards do conjunto (31)
- 1What is the Michaelis Menten EquationV = Vmax x [S] over [S] + Km
- 2What is the maximal velocity of a reaction?The point where the number of active sites are all occupied and the maximum amount of product is being produced - you can vary substrate concentration but you cant change the number of active sites
- 3What does the V stand for in the Michaelis Menten Equation?V = reaction velocity (the amount of product formed in 'x' time)
- 4What does Vmax stand for in the Michaelis Menten Equation?Vmax = maximum reaction velocity
- 5What does [S] stand for in the Michaelis Menten Equation?[S] = substrate concentration
- 6What does Km stand for in the Michaelis Menten Equation?Km = [S] that gives 50% of Vmax
- 7Why can you not work out Vmax from Km?You cannot double Km to get Vmax, and you cannot rearrange the calculation to do so. You can never theoretically reach Vmax.
- 8What is enzyme turnover number?The number of substrate molecules converted into product by an enzyme in 'x' amount of time when the substrate is fully saturated with substrate
- 9What does the Lineweaver Burk Plot / Double reciprocal plot enable?It enables Km and Vmax to be determined
- 10What is enzyme inhibition important for?Control mechanism, drugs and toxins, insight into enzyme mechanism of action
- 11What are the two types of enzyme inhibition?Reversible or Irreversible
- 12How do irreversible inhibitors work?They covalently or non covalently bind to the enzymes active site so that the substrate cannot bind
- 13What are some examples of irreversible inhibitors?Penicillin - inactivates a key enzyme in bacterial wall synthesis
Aklylating agents - inhibit the catalytic activity of some enzymes
Nerve gas - inhibits enzyme that plays important role in nerve impulse transmission - 14What are the two types of reversible inhibitors?Competitive and Noncompetitive
- 15What is the action of a competitive inhibitor?A competitive inhibitor has a similar shape to the substrate so it competes to bind with the active site
- 16How does a competitive inhibitor effect the Michaelis Menten Equation?Increases Km (because you need more substrate to outcompete the inhibitor)
No change in Vmax - 17Where does Vmax intercept on the Lineweaver Burk Plot?Vmax intercepts on the vertical 0 line
- 18Where does the Km line go on the Lineweaver Burk Plot?It intercepts on the horizontal x axis
- 19Describe this plot in terms of what happens to Km and Vmax when a competitive inhibitor is presentVmax does not change
Km increases - 20Describe what happens to this plot when a noncompetitive inhibitor is present.Vmax decreases
No change in Km
- 21What is the action of a noncompetitive inhibitor?The inhibitor and substrate can both bind at the same time, the inhibitor binds to a different site than the active site - by binding at a different site the inhibitor changes the shape of the protein causing a change in the active site shape and therefore the substrate will not fit as well
- 22What are allosteric enzymes?Enzymes that consist of multiple subunits and multiple active sites - binding of substrate to one site can affect the properties of the other active sites in the same enzyme
- 23What type of plot does an allosteric enzyme produce?A sigmoidal plot of V versus [S]
- 24What are the two forms of allosteric enzymes?T = tense
R = relaxed - 25What is the tense form of an allosteric enzyme and how does it effect KmTense enzyme binds the substrate poorly and it has a high Km
- 26What is the relaxed form of the allosteric enzyme and how does it effect Km?Relaxed enzyme binds the substrate readily and it has a Low Km
- 27Describe how the allosteric enzymes work in equilibrium when substrate is added.As substrate is increased, equilibrium shifts from the Tense state (poorly bound) to the Relaxed (readily bound) state resulting in a steep rise in activity
- 28How can the activity of allosteric enzymes be controlled?By regulatory molecules that bind to allosteric sites (a site other than the active site)
- 29What do allosteric inhibitors do?They stabilize the Tense form of the enzyme (less binding)
- 30What do allosteric activators do?They stabilize the Relaxed form of the enzyme (more binding)
- 31How does CTP work as an allosteric inhibitor?It inhibits the enzyme because it is the final product of the pathway so it binds to the enzyme to inhibit the pathway from making more CTP
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- FlashCards sobre Enzyme kinetics, criado por Olivia Hocking em 17-06-2015.
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- Olivia Hocking
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