enzyme inhibitors

• competitive inhibitors?

  same shape as the substrate so binds to the active site so the substrate molecule cannot enter. this forms an enzyme-inhibitor complex instead of an enzyme-substrate complex. the amount of inhibition depends on the concentration of substrate and inhibitor. increasing the substrate concentration can reduce the effects of the inhibitor as it is relatively less likely to collide with the enzyme. most competitive inhibitors are reversible, if the competitive inhibitor binds irreversibly it is called an inactivator
• C?

  C

  
• non-competitive inhibition?

  the inhibitor molecule binds to the enzyme at the allosteric site. This changes the shape of the active site and prevents the substrate from binding. fewer enzyme-substrate complexes can form, so the rate of reaction is reduced. some non-competitive inhibitors bind reversibly and some will bind irreversibly.
• c?

  c

  
• end-product inhibition?

  once the reaction has reached completion, the product remains bound to the active site, the enzyme can therefore not form any further product until the cell needs it, this is an example of negative feedback and prevents energy being wasted
• coenzymes are organic and cofactors are inorganic
• some cofactors and substrate together give the correct shape to fit the active site, other cofactors may change the distribution of charge at the active site

  prosthetic groups – cofactors that are permanently bound to an enzyme molecule

  coenzymes – small organic non-protein molecules that temporarily bind to the enzyme’s active site, just before or at the same time as the substrate.
• the cofactor of amylase is chloride ions
• vitamins are good sources of coenzymes.
• enzyme precursors?

  some enzymes are synthesised in an inactive precursor form, ensuring they are only used when needed. many digestive enzymes are produced this way so that they do not digest any of the cell’s molecules. an enzyme is activated by the binding of a cofactor which causes a change in the tertiary structure so the active site and substrate is complementary.