9/30 Enzyme Kinetics Flashcards
factors that affect rate of enzyme-catalyzed rxn
temperature, ph, [substrate], amount of enzyme
Km
the [substrate] at which half of the substrate binding sites are occupied (1/2 Vmax)
Vmax
100% of substrate binding sites are occupied
a large Km indicates what
low affinity between enzyme and substrate
a small Km indicates what
a high affinity between enzyme and substrate
first order rxn
at [substrate] below Km where less than 50% of the binding sites are occupied, almost a proportional increase in velocity as [sub] goes up
zero order rxn
at high [substrate] where 100% of the binding sites are occupied. rxn rate is no longer affected by [substrate]
reaction rate
amount of product formed per unit time
michaelis menten uninhibited rxn
lineweaver burke
allosteric kinetics, sigmoidal curve, cooperative, binding of first substrate increases enzyme’s affinity to bind additional substrates
ways to regulate enzymatic rxns
amount of enzyme present, location or assembly into functional oligomers, increase or decrease enzyme’s kinetic properties (zymogen, covalent modifications, comp/noncomp inhibitors, allosteric effectors)
types of inhibitors
irreversible and reversible (competitive and non-competitive)
effect of competitive inhibitors
increase the Km of the substrate, can be overcome by increasing [substrate]
effect of non-competitive inhibitors
lower Vmax and 1/2Vmax because its basically inactivating some enzymes, cannot be overcome by increasing [substrate]
competitive inhibition, Km changes
lineweaver burke non competitive inhibition, x-intercept is constant
allostery
changes in rxn kinetics induced by binding of effector molecule that results in altered enzyme structure
allosteric activator
changes structure to increase rxn rate, decreases Km
allosteric inhibitor
changes structure to inhibit reaction rate
allosteric inhibitors and activators affect the reaction rate
