Cofactors and Inhibitors Flashcards
1
Q
What are enzymes?
A
- Proteins that catalyse reactions
- Specific to one reaction due to the unique shape of their active site
- Work best at an optimum temperature
- Denature when hydrogen bonds break which changes the shape of the active site
2
Q
What are coenzymes?
A
- Organic molecules required for enzyme function
- Bind to the active site and participate in catalysis
- Often act as electron carriers or transfer atoms or functional groups
Example: NAD in electron transfer for dehydrogenase enzymes.
3
Q
What are prosthetic groups?
A
- Tightly bound molecules or ions required for enzyme function
- Can be organic or inorganic
- Often involved in the active site
Example: Zn²⁺ in carbonic anhydrase.
4
Q
What are cofactors?
A
Inorganic ions that increase the rate of catalysis
Example: Cl⁻ in salivary amylase.
5
Q
What are competitive inhibitors?
A
- Similar shape to the substrate so they bind to the active site
- Prevent enzyme-substrate complex (ESC) formation
- Reversible – adding more substrate outcompetes the inhibitor
Graph: Rate increases with more substrate until all active sites are occupied
6
Q
What are non-competitive inhibitors?
A
- Bind to an allosteric site
- Change the shape of the active site which prevents substrate binding
- Irreversible – adding more substrate does not restore enzyme activity
Graph: Plateaus at a lower rate, even with more substrate
7
Q
What is reversible non-competitive inhibition (end-product inhibition)?
A
- End-product of a reaction pathway inhibits the first enzyme
- Product levels increase- inhibition occurs - stops biosynthesis
- Product levels decrease- inhibitor leaves- restores enzyme function
8
Q
What are key variables in enzyme experiments?
A
- Controlled variables: Kept constant to ensure a valid experiment
- Control: Contains substrate but no enzyme or a denatured enzyme
- Independent variable: Factor being investigated
- Dependent variable: Factor measured
