enzyme inhibitors

Question 1

non-competitive inhibitors

Answer 1

bind to the enzyme away from the active site (allosteric site)
causing the active site to change shape
ESC cannot form
the rate of reaction is much slower

since it does not compete with the substrate for the active site, increasing the substrate concentration has no effect on overcoming the inhibition
the enzymes active site is altered so that even if the substrate bind, the reaction cannot proceed at the original rate

Question 2

competitive inhibitors

Answer 2

competitive inhibitors are a similar shape as the substrate and so it binds to the active site of the enzyme
this prevents the substrate from binding
most competitive inhibitors are reversible
once the inhibitors is removed, the reaction rate increases
the inhibitors can be ‘outcompeted’ at high substrate concentrations

Question 3

what is end-product inhibition an example of

Answer 3

non-competitive reversible inhibitor

Question 4

what is end-product inhibition

Answer 4

act as regulators in metabolic pathways
metabolic reactions must be very tightly controlled and balanced and so can be controlled by using the end-product of a particular sequence of metabolic reactions as a non-competitive reversible inhibitors
as the enzyme coverts the substrate into product, the process is itself slowed down as the end product of the reaction binds to an alternative site on the original enzyme, changing the shape of the active site and preventing the formation of further ESC
the end-product can then detach from the enzyme and be used elsewhere, allowing the active site to reform and the enzyme to return to an active state
this means that as product levels fall, the enzyme beings catalysing the reaction once again, in a continuous feedback loop

Question 5

non-reversible inhibitors

Answer 5

some inhibitors can form covalent bonds with enzymes, inhibiting them permanently - non-reversible or irreversible inhibitors
if this type of inhibition occurs in a living cell or organism it will result in the complete inactivation of the enzyme - this can be dangerous as can cause the biological reaction the enzyme is catalysing to be completely stopped
the only way to avoid this is for the cell or organism to produce more of the enzyme being inhibited, which can only be achieved by transcribing and translating the gene for the enzyme, which is a relatively slow process