Enzymes Flashcards
all enzymes are
catalysts
what do enzymes increase within a reaction
rate
how do enzymes increase the rate within a reaction
lowering the activation energy
are enzymes consumed within a reaction
no
what is the molecule in which enzymes act upon
substrate
what is the measure of an affinity that an enzyme has towards the substrate
Km
what kind of relationship do Km and affinity have
decrease Km, increase affinity
inverse relationship
what is the max velocity of an enzyme
Vmax
1/2 of vmax=
Km
what are the 3 major factors that affect the reaction velocity of an enzyme
substrate concentration
temperature
pH
what is the maximal velocity of an enzyme catalyzed reaction
Vmax
what is the amount of substrate required to reach 1/2Vmax
Km
what are the competitive inhibitors
- increase the Km
- no change in Vmax
what are the non competitive inhibitors
- no change int he Km
- decrease the Vmax
what do competitive inhibitors do
- bind to substrate binding site of enzyme
- increase Km (lower affinity)
- can add enough substrate to dilute out inhibitor
what do the non competitive inhibitors do
- binds to site other than substrate binding site
- no change in Km (because affinity for binding site has not changed)
- decrease in vmax: will take longer to reach Vmax
what are the type of enzymes that act as the rate limiting steps for an entire metabolic pathway
allosteric enzymes
what modulates allosteric enzyme activity
allosteric effectors
what is an example of an allosteric effector
PFK is allosterically inhibited by an increase of ATP
what is the measure of the amount of energy available to determine if a reaction is energetically feasible
Gibbs free energy
deltaG=0
equilibrium
deltaG= +
rxn is non-spontaneous/unfavorable
deltaG= -
rxn is spontaneous/favorable
what is Gibbs free energy if the energy of the rxn -4.17
exergonic
spontaneous
favorable
