Essential Cell Biology 5th edition

172 CHAPTER 4 Protein Structure and Function
Substrate Concentration
(μM)
Reaction Rate (μmole/min)
0.08 0.15
0.12 0.21
0.54 0.7
1.23 1.1
1.82 1.3
2.72 1.5
4.94 1.7
10.00 1.8
1/rate versus 1/[S] as a new graph. Determine K M and V max
from the intercept of the line with the axis, where 1/[S] = 0,
combined with the slope of the line. Do your results agree
with the estimates made from the first graph of the raw
data?
C. It is stated in part (A) that only very little product
was formed under the reaction conditions. Why is this
important?
D. Assume the enzyme is regulated such that upon
phosphorylation its K M increases by a factor of 3 without
changing its V max . Is this an activation or inhibition? Plot the
data you would expect for the phosphorylated enzyme in
both the graph for (A) and the graph for (B).