Enzymatic Kinetics Flashcards
when do we use michaelis and menten
to determine if an enzyme is physiologically useful based on its maximum rate and affinity for substrate (or inhibitor or coenzyme)
1st order: Concentration of a _____ substrate is directly
proportional to the rate of the reaction
single
____ first order is when an enzyme uses two substrates BUT only one substrate affects it’s rate
pseudo
when an enzyme becomes saturated, it is called the ____ on the graph
zero order
- the enzyme is used up so even if you add more substrate, there will be no effect. The speed will no longer be effected
Vmax =
maximum velocity
Km =
enzyme affinity
(1/2 Vmax)
small Km =
high affinity
large Km =
low affinity
Vo
initial velcocity
Y-intercept = 1/Vmax
Lineweaver-Burk = reciprocal of M & M equation
Extrapolated X-intercept = - 1/Km
Lineweaver-Burk = reciprocal of M & M equation
the primary carbohydrate stored in the liver and muscle cells of animals, from glucose
glycogen
what measures speed of P formation once ES has been made?
Kcat
what measures binding affinity of E and S to make ES
km
If Kcat is large…
the enzyme will be more efficient
If the Km is low…
enzyme will be more efficient
smaller Kcat/Km
would not be as efficient
Reversible binding of the inhibitor to the active site of the enzyme
Competitive inhibition
Inhibition where the inhibitor binds to the enzyme-substrate complex
uncompetitive
Inhibition is where the inhibitor binds to the enzyme or enzyme-substrate complex at a site other than the active site
non-competitive
Inhibition that forms a covalent bond with the enzyme’s active site
irreversible enzyme inhibition
Pb+2 binds to _____ groups in an enzyme
involved in heme synthesis. Changes its shape so it no longer functions. What is the phenomena?
sulfhydryl
Lead poisioning
Penicillin ____ the enzyme required for synthesis of bacterial cell
walls
blocks
Enzymes with multiple subunits that are regulated by activators and inhibitors
allosteric enzymes
On a sigmoidal group, an inhibitor, produces a _____ shift
right
no change in vmax. increase in km
competitive
- higher km = lower affinity because now the substrate concentration needs to be higher
reduced vmax. reduced km
uncompetitive
- lower km = higher affinity
inhibitor doesn’t bind until E binds to S
reduced vmax. unchanged km
noncompetitive
- active site is not competed for so no change in km
Which site has a higher affinity? Active or allosteric?
Active site: higher affinity because it works at a lower concentration of ATP
Allosertic site: needs a higher sensitivity so is therefore, lower affinity
