enzymes Flashcards
what are some characteristics of enzymes?
- high molecular weight
- biological catalysts
- denature at high temps/pH
- specific to reactions they catalyse
what is meant by induced fit?
- proteins have 3D flexibility
- once bound to a substrate, enzymes change shape to form an exact fit
why are enzymes catalysts?
they lower the activation energy needed to drive a reaction
why do high temperatures denature enzymes?
- bonds that stabilise secondary and tertiary structures are broken
- enzyme loses its shape and the active site is altered
- can no longer fit the substrate
what is optimum temperature and how does it work?
- max temperature before enzymes denature
- useful as the molecules are colliding more frequently so there is a higher chance of successful collisions
why must pH be kept constant?
- hydrogen bonds are unaffected
- active site remains unchanged
- substrate can successfully bind
why does pH denature enzymes?
- lower pH means more hydrogen ions
- this breaks the forces of attraction ad bonds that hold enzymes together so they lose their shape
what are competitive inhibitors?
molecules similar to the substrate bind to the enzyme
what is the effect of competitive inhibitors?
- ROR is decreased
- can reach maximum ROR but at a slower rate
- this can be overcome by increasing substrate concentration
what are non- competetive inhibitors?
molecule binds to a different part of the enzyme so the substrate still fits but induced fit cannot occur
what are the effects of non-competitive inhibitors?
- ROR is reduced and can never reach maximum rate of reaction
- increasing substrate concentration does NOT effect these inhibitors
describe and explain how a normal reaction profile would change if the reaction was catalysed by an enzyme.
- activation energy is lowered
- substrate and product energy stay the same
- substrate fits into active site and form an enzyme substrate complex
- force exerted on bonds in substrate so lowers activation energy
what is an intracellular enzyme and give examples?
produced and function inside cell
- catalase
- polymerase
- helicase
what is an extracellular enzyme and give examples?
transported out of the cell by vesicles
- amylase
- lipase
- protease
what is feedback inhibition?
end product acts as an inhibitor to stop enzyme reactions
