2) Enzyme Activity: Kinestics & Inhibition Flashcards
What is the transition state in a chemical reaction?
The high energy intermediate that lies between the start and end of a reaction
What is the activation energy in a chemical reaction?
The minimum energy needed by the reactants to allow a reaction to occur
How does increasing temperature cause an increase in the rate of reaction?
Increases the number of molecules with activation energy
How does increasing the concentration of molecules cause an increase in the rate of reaction?
Increases the frequency of successful collisions
How does a biological catalyst increase the rate of reaction?
Decreases the activation energy
List 4 important features of enzymes
- Highly specific
- Unchanged after a reaction
- increase the rate of reaction
- don’t affect the reaction equilibrium
What is an active site?
A cleft or crevice on the enzyme where a substrate binds and the chemical reaction takes place
What is the basic structure of an enzyme?
Active site - a few amino acids from different parts of the primary sequence
Scaffolding - typically >100 amino acids
Why is the active site a cleft or crevice?
To exclude water which can interfere with the chemical reaction
How do enzymes & substrates have complementary structures?
1) The active site and substrate have similar complementary structures and can bind together
2) Binding of the substrate to the active site induces a change to the shape of the active site making it complementary to the substrate
How are enzymes and substrates bound?
Non-covalent bonds:
- VDWs
- Hydrogen bonds
- electrostatic
Why is the bonding between an enzyme and substrate weak?
To prevent tight binding so that the change can be reversed
What is Km?
The concentration of substrate bound at half of the maximal velocity
What does a low Km mean?
Enzyme has a high affinity for the substrate
