8.1 HL Flashcards
what are the two types of inhibition what do they do to enzymes
competitive and non-competitive
reduce/ stop the activity of enzymes
competitive inhibitors
chemical that bind to the active site and prevent the substrate from combining with the enzyme.
chemically similar to the substrate
how does competitive inhibitators prevent enzyme activity
binds to the active site which prevent the substrate from binding
if the amount of substrate is increased then the substrate collisons will increase and eventually there will be more substrate collisions than inhibator collisons
non- compertitive inhibitators
do not bind to the active site.
bind to a different site on the enzyme and change the shape of the active site.
the substrate may still be able to bind to the active site, however, the enzyme is not able to catalyse the reaction or can only do o at a slower rate.
not similar to the substrate.
examples of competitive inhibition
ethanol is metabolised in the body by oxidisation to acetaldehyde.
- this is then further oxidised to acetic acid via aldehyde with subsequent
unpleasant side-effects of nausea and vomiting.
- this is sometimes used to help people overcome drinking habits
many antibiotics are competitive inhibitators of growth factors that are needed in bacterial metabolism
metabolic pathways
complex with many small reactions making intermediate compounds, each controlled by its own enzyme.
some pathways are chains
metabolic pathways consist of chains and cycles of enzyme-catalysed reactions.
end-product inhibition
a form of negative feedback when increased levels of product decrease the rate of product formation.
because of metabolic pathways being made of chains or cycles, the product can regulate the rate of its own production by inhibiting an earlier enzyme in the metabolic pathway.
the product then binds to an allosteric site of an enzyme, causing a conformational change in the active site.
because the enzyme cannot function, the rate of product formation decreases ans with less product there is less enzyme inhibition.
example of end-product inhibition
the ATP formation by phosphofructokinase.
ATP inhibits phosphofructokinase so that when the ATP levels are high, glucose is not broken down, but instead can be stored as glycogen.
When ATP levels are low, phosphofructokinase is activated and glucose is broken down to make more ATP.
