Enzymes Flashcards
what are enzymes
proteins-act as biological catalysts for intra and extra cellular reactions
specific tertiary structure determines shape of active site-complementary to substrate
enzyme substrate complex formation lowers activation energy
give an example of an enzyme that catalyses intracellular reactions
catalase
decomposition of hydrogen peroxide into oxygen and water
is amylase an extracellular or intracellular enzyme
extracellular
digestion of starch to maltose in saliva
how is trypsin extracellular
hydrolysis of peptide bonds in small intestine lumen
explain the induced fit model
shape of active site is not directly complementary and is flexible
conformational changes allow enzyme substrate complexes to form
puts strain on substrate bond lowering activation energy
bonds in enzyme product complex are weak so product desorbs
explain the lock and key theory
active site has rigid shape complementary to only one substrate
formation of enzyme substrate complex lowers activation energy
bonds in enzyme product complex weak so product desorbs
what 5 factors affect enzyme controlled reactions
enzyme concentration
substrate concentration
inhibitor concentration
pH
temperature
how does substrate concentration affect rate of reaction
rate increases proportionately to substrate concentration
rate levels off when maximum number of enzyme substrate complexes formed
how does enzyme concentration affect rate of reaction
if substrate in excess rate increases proportionately to enzyme conc
levels off when maximum number of enzyme substrate complexes
how does temperature affect rate of reaction
rate increases as kinetic energy increases until reaches optimum temperature
above optimum temperature, ionic and H+ bonds break ao active site no longer complementary
how do competitive inhibitors work
bind to active site as have similar shape
prevent enzyme substrate complexes forming
increasing substrate concentration decreases their effect
how do non competitive inhibitors work
bind to allosteric site
trigger change in active site
what is end product inhibition
one of the products as a competitive or non competitive inhibitor
prevents formation of products
what are irreversible inhibitors
permanently prevent formation of enzyme substrate complexes
what are cofactors
non protein compounds required for enzyme activity
