Enzymes Flashcards
if a holoenzyme uses a small organic molecule as its non-protein component its called a ______
Coenzyme
If a Holoenzyme uses a metal ion as its non-protein component, its called a ________
cofactor
a holoenzyme w/o its non protein component (and is inactive) is a _______
apoenzyme
what is the free energy of activation?
the difference in energy between the reactants and products that must be overcome for the reaction to proceed
what is the rate or velocity of a reaction?
number of substrate molecules converted to product per unit of time
what is maximal velocity of a reaction?
when all the binding sites are taken on enzyme molecules in a reaction
what is Km?
an enzyme’s affinity for a substrate
another way of putting it: the amount of substrate needed to reach 1/2 Vmax
when your [S] concentration is less than Km, what does that mean about velocity of the reaction?
it is first order- it is proportional to the amount of [S]
When your [S] concentration is greater than Km, what does that mean about the velocity of the Km?
It is constant and equal to the Vmax- zero order
where are Vmax and Km on a LB plot?
X intercept= 1/Km
Y intercept= 1/Vmax
how does a competitive inhibitor affect the vmax and Km values?
Vmax- stays the same
Km- increases because you need more substrate to reach Vmax (lowers affinity)
what effect on the Vmax and Km does a noncompetitive inhibitor have?
Vmax is lowered (different Y intercept)
Km is the same (x intercept)
what affect do positive effectors have?
increase enzymatic activity
lower Km
raises the Vmax
what affect do negative effectors have?
lower enzymatic activity
lower Vmax
raise Km
fasting activates what covalent modifications?
activates kinases that phosphorylate enzymes
activated enzymes= catabolism (breaking down)
inactive enzymes= those for anabolism (synthesis)
