Enzyme Kinetics Flashcards
What does Vmax mean?
- is the maximum is when enzymes are at their highest rate and completely saturated with their substrates.
- Hence ‘V’ for velocity
What does [S] stand for?
-Substrate Concentration
What does Km mean?
- Michaelis Constant
- Substrate Concentration in moles where Vmax is half maximal value
- Also Rate Constant of disappearance of the Enzyme-Substrate concentration which was formed in the reaction at Activated Complex
- Shows enzyme affinity
What is Michaelis-Mentin Model used for?
-Explains relationship between Km and Vmax
What does K1 mean?
Rate Constant:
-K1- Rate Constant for Enzyme Association with Substrate E + S > ES Complex
What does K2 mean?
Rate Constant:
- ES > E+P
- Formation of product from enzyme and substrate reacting
What does K-1 mean?
Rate Constant:
-Backwards reaction when enzyme dissociates from Substrate in (ES) Complex
What does V0 mean?
-Rate of product increase
How can Vmax and KM be calculated in an experiment?
-Repeat at different substrate concentrations
Why is Vmax and KM not always easy to determine?
-Vmax never reaches its true value
What X2 things is the Michaelis-Mentin Equation used for?
- Rate of substrate catalysis
- Calculates velocity
What can Michaelis-Mentin Equation be arranged to and what for?
- Straight line equation
- Lineweaver Burke Plot
What type of curve does the Michaelis Model form?
-Sigmoidal
What type of graph does the Lineweaver Burk Plot have?
-Straight line
What is the relationship between the Michaelis Mentin Model and Lineweaver Burke Plot?
- Inverse relationship of values
- Lineweaver calculates values by 1/ Value
Where can the Vmax and Km values be found on the Lineweaver Burke Plot?
- Vmax- Y Intercept
- Km- X intercept
What does a Low Km value mean?
-Enzyme only needs a small amount of substrate to work at Km
What does a High Km value mean?
-Enzyme needs a LARGE amount of substrate to work at its Km
What are the two types of enzyme inhibition?
Reversible and Irreversible
What are the two types of Inhibitors and which can be reversible/ irreversible?
- Competitive (Reversible)
- Non-Competitive (BOTH-Reversible/Irreversible)
How does a Competitive Inhibitor work?
- Inhibitor binds to active site -‘Orthosteric Site’
- Prevents substrates from binding
- Inc. substrate concentration decreases competitive inhibition but can reach ‘Saturation’
How does a Reversible Non-Competitive Inhibitor work?
- Inhibitor binds to another part of the enzyme
- Temporarily changes enzyme conformation so the substrate no longer fits.
How does an Irreversible Non-Competitive Inhibitor work?
- Binds to enzyme and breaks covalent bonds
- Inhibitor cannot be removed
What is Feedback Inhibition?
End-Product formed inhibits early stage of reaction pathway
