Flashcards in Enzymes 1 Deck (20)
What is an enzyme cofactor?
a nonprotein part required for activity
What is a coenzyme?
a complex organic molecule usually produced from a vitamin e.g NAD-
What is a prosthetic group?
cofactor covalently bound to the enzyme or very tightly associated with the enzyme
What is an apoenzyme?
protein component of an enzyme that contains a cofactor
What is a holoenzyme?
the whole enzyme - the apoenzyme AND the cofactor(s)
What do enzymes do? (3 things)
-increase RATES of spontaneous reactions
-lower the activation energy of biochemical reactions
-accelerate movement towards reaction equilibrium
What do enzymes NOT do? (2 things)
-move reaction equilibria
-make a non-spontaneous reaction spontaneous
What is Gibb's Free Energy?
'useful' energy - the energy that is available
What delta G value must a spontaneous reaction have?
What is the calculation of of Gibb's Free Energy?
delta G= deltaH-TdeltaS
What happens to a reaction if there is no enzyme?
there is a high activation energy
What is the optimum shape of the active site in relation to the substrate?
active site complimentary to transition state
How do enzymes reduce activation energy? (3 ways)
What is meant by desolvation?
weak bonds between substrate and enzyme essentially replace most or all of H bonds between substrate and aqueous solution
What is meant by induced fit?
conformational change occurs in protein structure when substrate binds
Why does Vmax occur?
because all the enzyme active sites are saturated with substrate
What does V0 usually equate to?
the steady state of a reaction
What is the Km equivalent to?
the substrate concentration at which the initial reaction rate is half of the maximum reaction rate
What does Km tell you?
the affinity of an enzyme with its substrate