4.2 (2.1.4) Factors affecting enzyme activity

explain how low temperatures affect enzyme activity

enzyme activity is low because the enzyme and substrate molecules have less kinetic energy, therefore decreased frequency of successful collisions between enzymes and substrates, fewer e-s complexes made, fewer e-p complexes made

explain how enzyme activity changes at the optimum temperature

highest rate of enzyme activity as enzymes and substrate have enough kinetic energy, increased frequency of successful collisions, more e-s complexes formed, more e-p complexes formed

explain how enzyme activity changes at higher temperatures past the optimum

enzyme activity decreases, the bonds holding the protein together vibrate more, the vibrations increase until the bonds strain and break resulting in a change is the specific tertiary structure of the protein, enzyme has been denatured, fewer e-s complexes form, fewer e-p complexes form

explain how enzyme activity changes with a low pH below the optimum

enzyme activity decreases, the more hydrogen ions present the less the variable groups are able to interact with each other, leads to bonds breaking and the shape of the enzyme changing

explain how enzyme activity changes at the optimum temperature

highest rate of enzyme activity, specific tertiary structure of active site is not changed by the concentration of hydrogen ions

explain how enzyme activity changes at higher pHs above the optimum pH

enzyme activity decreases, hydrogen ions interact with polar and charged variable groups, tertiary structure of enzyme is irreversibly altered, active site no longer complementary to the substrate

how does increasing the substrate concentration increase the rate of reaction

more substrate molecules, increased frequency of successful collisions between active sites and substrates, more e-s complexes formed, more e-p complexes formed

define V_max

all of the active sites are occupied by substrate particles and no more e-s complexes can be formed until products are released from active sites

define Q₁₀

a measure of how much the rate of reaction increases with a 10°C rise in temperature