Enzymes Flashcards
what are enzymes
biological catalysts
how do enzymes affect the equilibrium?
enzymes do not alter the equilibrium but they accelerate the time to reach equilibrium
what is the only enzyme that is not a protein?
ribozymes
what is enzyme activity of proteins dependent on?
their 3D structure
what is enzyme activity affected by?
temperature and pH
what is standard free energy change?
difference between energies of reactants and products
what is the activation energy?
the energy input required to initiate reaction
what does an increase in enzyme concentration do?
increases the reaction rate
what is the Vmax?
maximum rate of reaction
what is the Km?
concentration of substrate at which the rate of reaction is half its maximum value
comment on irreversible inhibitors
damage enzymes beyond repair. generally cause covalent modification of the enzyme
comment on reversible inhibitors
full enzyme activity is regained when the inhibitor is removed. most natural enzyme inhibitors fall into this category
what is feedback inhibition
when the product of a metabolic pathway builds up in the cell, inhibition of the pathway often occurs because the product of the pathway acts as a inhibitor of an earlier step in the pathway
what is a competitive inhibitor
substrate and inhibitor compete for same active binding site. inhibition can be reversible with large quantities of substrate
what is a non-competitive inhibitor
binds to an allosteric site on the enzyme. structurally unrelated to substrate. inhibition cannot be reversed by adding large quantities of substrate