Physiology and metabolism 1-7 Flashcards
How do enzymes affect the chemical equilibrium
Enzymes have no effect as they increase the forward and backward reaction
How is catalytic power expressed
The turnover number or catalytic constant (Kcat)
Define Kcat
The number of molecules of substrate that one enzyme molecule can convert in 1 second
What are co-factors
Small molecules not part of the enzyme but are required for activity. These can be metal ions or other organic molecules
Enzymes classifications
- Oxidoreductases
- Transferases
- Hydrolases
- Lyases
- Isomerases
- Ligases
What is the active site
Part of the enzyme in contact with the substrate. Many weak non-covalent interactions form between the substrate and active site.
How is the active site formed
It is a 3-dimensional structure formed from the folding of the polypeptide chain.
What is the lock and key model
Active sites were initially pictured as a fixed set of chemical groups exactly fitting the substrate.
What is the induced fit model
Continuous change in the conformation and shape of the enzyme in response to substrate binding. Allows a greater degree of specificity as they also have to interact.
What is a transition state
The highest energy state interval along the pathway from substrate to product.
What is the activation barrier
The difference in energy between reactants and the transition state.
How do enzymes speed up the rate of the reaction
They lower the activation barrier by providing an alternative pathway which stabilises the transition state.
Another name for enzyme substrate complex
Michaelis complex
What is a catalytic triad
A group of 3 amino acids found on the active site of some proteases involved in catalysis. They form part of the active site.
Conditions needed for steady state kinetics
substrate»_space; enzyme
