BCH 361 Lecture Notes - Lecture 2: Specific Activity, Dissociation Constant
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1. A) Activity refers to the amount of enzyme transformed in a specific number of unit time. In my
answer, I used micromoles per minute.
a. 12 millimoles -> 12000 μm.
b. Activity = enzyme transformed / unit time = (12000 μm) / (2 min) = 6000 μm/min
c. B) Specific activity refers to the units of activity per mg
d. Specific activity = activity / total mg of enzyme = (6000 μm/min) / (24 mg) = 250
μm/min*mg
2. At substrate concentrations, near the Km, the enzyme displays significant catalysis yet is
sensitive to changes in substrate concentration.
3. The sequential reactions are characterized by the formation of a ternary complex
consisting of the enzyme & both substrates. Double-displacement reactions always
require the formation of a ternary complex consisting of the enzyme and both substrates.
Double-displacement reactions always require the formation of a temporary substituted
enzyme intermediate.
4. Km is the Michaelis-Menten constant which represents the concentration of the
substrate when the rate of reaction is equal to '1/2' of the maximum velocity for the
reaction. It can also be thought of as a measure of how well a substrate complexes
with a given enzyme, otherwise in common it is known as its binding affinity.
a. And as mentioned above when
b. Rate of reaction = ( Rate )max/2
c. Then Km = Kd
5. A.Rate = [S t2] - [S t1] / t2-t1 = mol/min
Initial concentration (μmol/mL)
Initial Rate (mol/min)
0
0.2
2.32
1.164
3
1.376
4.55
1.645
12.66
2.38
38.50
2.76
200.00
3.18