Enzymes Flashcards
Why do some reactions with a negative delta G occur slowly or not at all?
-They have not passed the activation energy threshold required to conver the reactants into unstable ‘transition-state species’
Heat is not feasible as a factor to alter in order to surpass activation energy threshold. How do enzymes overcome the issue of activation energy?
Enzymes alter the nature of the transition-state species, such that the activation energy threshold is much lower
What are the chemical events at active sites?
- Orienting substrates
- Adding Charges
- Inducing Strain
What occurs to the enzyme when it binds to substrate?
it changes shape to the transition state of the substrate
What are the six broad categories of enzyme?
- Oxidoreductases
- Transferases
- Hydrolases
- Lyases
- Isomerases
- Ligases
What do ligases do?
Join molecules together
What do isomerases do?
Catalyse intramolecular rearrangement
What do lyases do?
Catalyse removal of a group to form a double bond or addition of a group to a double bond, or other cleavages involving electron rearrangement
What do oxidoreductases do?
Catalyse the transfer of electrons from a donor to an acceptor (H+ transfer can also occur)
What do transferases do?
Catalyse the transfer of functional groups such as phosphate, methyl, etc. from one molecule to another
What do hydrolases do?
Catalyse the cleavage of bonds through addition of water or vice versa
what are co-factors?
non-protein factors which are essential for enzyme activity
What are coenzymes?
Carbon containing cofactors, temporarily bound to enzymes, derived from water soluble vitamins
What are prosthetic groups?
Covalently bound to enzymes
What is a holoenzyme?
Enzyme with prosthetic group
