 Oct 24, 2012
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 Dentist
Please help!
In order to solve the problem below, you need the following information:
Question 6 and 7 provided this equation "y = 2 x + 0.5" and asked us to solve for Vmax and Km, giving Vmax = 2 "s" and Km=4 mM (s were some arbitrary units given). Easy enough...
Now to the actual question:
Following questions 6 and 7, in the presence of 3 mM inhibitor Y, LineweaverBurk plot of enzyme X in question 6 can be fit to equation y = 6 x + 0.5. This inhibitor is:
a. competitive with KI of 0.6 mM
b. competitive with KI of 1.5 mM
c. competitive with KI of 3 mM
d. uncompetitive with KI' of 3 mM
e. uncompetitive with KI' of 6 mM
According to my Biochem professor, the answer is "B".
Here's my sortof solution:
We know off the bat it's a competitive inhibitor because the yintercept stays constant, so D and E are out immediately.
Now, I use the equation for competitive inhibition:
[(1/Vo) = (αKm)/Vmax][1/] + (1/Vmax)
We want to solve for Ki, we're given = 3 mM, and we know α = 1 + /Ki
We know that when y = 0, the x intercept is equal to (1/km). So, setting "y" (1/Vo) equal to 0 and solving for "x" (1/), we get 0.08333. Solving for km, we get km = 12
So now that we have km, I set [(αKm)/Vmax] equal to 6 (from the equation given in the question), and solved for α, giving α = 1
Finally, using the equation α = 1 + /Ki, I tried to solve for Ki using the values (α = 1, = 3 mM) and Ki ends up being undefined (1 = 1 + 3/x)
Does anyone see where I'm going wrong?
Thanks in advance for trying to solve this problem... Maybe it'll help you understand enzyme kinetics more in the process for your biochem final!
In order to solve the problem below, you need the following information:
Question 6 and 7 provided this equation "y = 2 x + 0.5" and asked us to solve for Vmax and Km, giving Vmax = 2 "s" and Km=4 mM (s were some arbitrary units given). Easy enough...
Now to the actual question:
Following questions 6 and 7, in the presence of 3 mM inhibitor Y, LineweaverBurk plot of enzyme X in question 6 can be fit to equation y = 6 x + 0.5. This inhibitor is:
a. competitive with KI of 0.6 mM
b. competitive with KI of 1.5 mM
c. competitive with KI of 3 mM
d. uncompetitive with KI' of 3 mM
e. uncompetitive with KI' of 6 mM
According to my Biochem professor, the answer is "B".
Here's my sortof solution:
We know off the bat it's a competitive inhibitor because the yintercept stays constant, so D and E are out immediately.
Now, I use the equation for competitive inhibition:
[(1/Vo) = (αKm)/Vmax][1/
We want to solve for Ki, we're given = 3 mM, and we know α = 1 + /Ki
We know that when y = 0, the x intercept is equal to (1/km). So, setting "y" (1/Vo) equal to 0 and solving for "x" (1/
So now that we have km, I set [(αKm)/Vmax] equal to 6 (from the equation given in the question), and solved for α, giving α = 1
Finally, using the equation α = 1 + /Ki, I tried to solve for Ki using the values (α = 1, = 3 mM) and Ki ends up being undefined (1 = 1 + 3/x)
Does anyone see where I'm going wrong?
Thanks in advance for trying to solve this problem... Maybe it'll help you understand enzyme kinetics more in the process for your biochem final!