factors affecting enzymes Flashcards
what are the factors that affect the rate of enzyme controlled reactions ?
- temperature
- pH
- enzyme concentration
- substrate concentration
- inhibitors
why are proteins sensitive to certain conditions ?
due to the bonds that hold them together in the tertiary structure of the protein
draw the graph for the effect of temperature on enzymes
notes
what occurs at point 1
molecules gain kinetic energy and collide more frequently to produce enzyme-substrate complexes more quickly
- more substrates can overcome the activation energy
what is the peak of the graph representing ?
this is the optimum temperature of the enzyme
what occurs at point 3 ?
enzymes denature which is irreversible
why do enzymes denature ?
the high temperature causes the bonds in the tertiary structure of the active site to break and the active site changes shape so that it is not longer complementary to the substrate
- so no enzyme-substrate complexes can be formed
draw the graph for the effect of pH
notes
what happens when the conditions are too acidic ?
it produces too many H+ ions which bind to the R groups and interferes with hydrogen bonds and the charges in the amino acids
what happens if the conditions are too alkaline ?
it produces too many OH - ions which interfere with the ionic bonds
what do both conditions cause ?
they will interfere with the charges in the amino acid in the active site. which can break the bonds holding the tertiary structure in place and therefore the active site changes shape so fewer enzyme-substrate complexes form
what do different enzyme shave in terms of pH ?
different enzymes have different optimal pH
draw the graph for substrate concentration
notes
what occurs at point 1 on the sc graph
more substrates means that more enzyme substrate complexes are produced
what occurs at point 2 on the sc graph ?
substrates run out of active sites to bind to and the speed of enzyme-substrate complexes forming is stable
draw the graph for enzyme concentration ?
notes
what occurs at point 1 on the ec graph ?
more enzymes means that more enzyme substrate complexes are produced
what occurs at point 2 on the ec graph ?
the limiting factor becomes the concentration of substrates
what are the 2 types of enzyme inhibitors ?
- competitive inhibitors
- non- competitive inhibitors
what is meant by a competitive inhibitor ?
competitive inhibitors are the same shape as the substrate and can bind to the active site
- this prevents the substrate from binding and the reaction to occur
what do competitive- inhibitors do ?
compete for the active site
how do you reduce the effect of the competitive inhibitor ?
you increase the substrate concentration
- because the higher the the substrate concentration there more likely it is that the substrate will bind to the active site and out compete the inhibitor, knocking them out of the active site
draw the graph for the competitive inhibitor
notes
what is meant by a non-competitive inhibitor ?
they bind to the enzyme away from the active site
- this causes the active site t change shape and therefore the substrate can no longer bind regardless of how much substrate is added
