enzymes Flashcards
what is an exergonic reaction
a chemical reaction that releases energy
what is an endergonic reaction
a chemical reaction that requires energy
what is activation energy
the energy required to make the reaction happen
what is the transition state
the point of maximum energy requirement
how do enzymes work as catalysts
they lower the activation energy by providing an alternative transition state
what are lysozymes
a natural antibiotic which attacks bacterial cell walls killing the bacteria
how does the induced fit model work
contact between binding site and substrate induces a change in shape of the active site to bind to the substrate
what affects enzyme activity
time
pH
temperature
substrate concentration
what does pH affect in enzymes
changes in pH affect electrostatic bonds
- active site is altered
- substrate charges change
what 2 effects does temperature have on enzymes
- kinetic
- denaturing
what is Km
[S] at half Vmax
what is Vmax
the fastest rate at which an enzyme can work, only occurs at infinite [S]
where do irreversible inhibitors bind to
an amino acid side chain at or near the active site
how do irreversible inhibitors prevent enzyme - substrate complexes forming
usually prevents substrate binding
what do competitive inhibitors compete with for access to where
they compete with substrates for access to active sites
how can competitive inhibitors be overcome
by increasing [S] until it out-competes inhibitors
where do non-competitive inhibitors bind
bind at a site other than active site (allosteric) so doesn’t prevent the substrate binding to the enzyme
how can non-competitive inhibitors be removed
removed by repeated dialysis
how do non-competitive inhibitors prevent catalytic activity
it alters the active site shape of enzyme so substrate binds less efficiently and no E-S complexes form q
