Lecture 7 Flashcards
What is ΔG?
Gibbs energy, measure of spontaneity
When ΔG < 0
The reaction is spontaneous, energy released
When ΔG > 0
The reaction is non-spontaneous, energy required
When ΔG = 0
The reaction is at equilibrium, no work can be done
How do enzymes catalyse thermodynamically favourable reactions?
By providing an alternate pathway of lower energy
What is required for a reaction to reach a high-energy transition state?
Activation energy supplied
What is the activation energy, as read off a reaction progress graph?
The difference in energy between the reactants and the activated complex/transition state
How do enzymes influence forward and reverse reactions?
By decreasing activation energy, the forward and reverse reactions are accelerated equally
What is the symbol for activation energy?
Ea OR ΔG‡
How does ΔG change when an enzyme is introduced to a reaction?
There is no change, only ΔG‡ decreases
What type of molecule makes up the majority of enzymes?
Proteins
What are the main classes of enzymes?
Oxidoreductase, Transferase, Hydrolase, Lyase, Isomerase, Ligase
What are oxidoreductase enzymes?
RedOx enzymes, transfer electrons
What are transferase enzymes?
Transfer enzymes, of functional groups
What are hydrolase enzymes?
Hydrolysis enzymes, using H2O
What are lyase enzymes?
Non-hydrolytic enzymes, for breaking or making bonds not involving water
What are isomerase enzymes?
Transfer of atom or group enzymes, within a molecule to yield an isomeric form
What are ligase enzymes?
Joining of two molecules together (Forming a new bond, usually coupled to ATP
What are cofactors?
Non-protein factors that help catalyse reactions
What are the classes of cofactors?
Metal ions and co-enzymes
Describe metal ions
Lewis acids that form coordination compounds with precise geometries
What are examples of metal ions?
Mg2+, Zn2+, Fe2+, Fe3+
What are the enzymes related to Mg2+?
DNA polymerase, hexokinase, Pyruvate kinase
What are the enzymes related to Zn2+?
Alcohol dehydrogenase, carbonic anhydrase
