BCH 361 Lecture Notes - Lecture 3: Microsoft Powerpoint, Transferase, Alcohol Dehydrogenase

18 views4 pages
9 Nov 2020
Department
Course
Professor
BCH 361 Advanced Biochemistry I Fall 2020
1
Group Discussion Questions
Week 3 (September 21/22)
1. Kinetics PowerPoint slides 24/25. Solve the problems and compare your answers with your
groupmates.
2. What is the biochemical advantage to having a KM approximately the same as the substrate
concentration that is normally available to the enzyme?
3. What is the defining characteristic of an enzyme catalyzing a sequential reaction? A double-
displacement reaction? (How can you tell these apart?)
4. The affinity between a protein and its ligand is frequently reported as a dissociation constant, Kd.
Does KM measure the affinity between the enzyme and the substrate? Under what circumstances
might KM be approximately the same as Kd?
5. A substrate, S, was cleaved by an enzyme and the rate of disappearance measured every 30 seconds
for 3 minutes. A series of six test tubes was arranged with 1.5 µg of enzyme (MW 30 000 Da) being
added to the same volume of substrate solution, but with each at a different concentration. The
results are summarized in Table 1.
Table 1. Raw data for stopped enzyme assay
Time
(min)
Substrate reacted (µmol)
S0
S1
S2
S3
S4
S5
0.5
1.0
1.5
2.0
2.5
3.0
0.0
0.1
0.2
0.3
0.4
0.5
0.49
1.05
1.66
2.23
2.81
3.40
0.56
1.23
1.93
2.61
3.30
4.00
0.71
1.52
2.36
3.18
4.00
--
1.10
2.24
3.48
--
--
--
1.36
2.74
--
--
--
--
Initial conc.
(µmol/mL)
0.00
2.32
3.00
4.55
12.66
38.50
a. What are the initial velocities at each substrate concentration? [Hint: it’s easiest to use
Excel or a similar spreadsheet for this problem.]
b. Determine the vmax and KM values for the enzyme using graphical techniques. Use more
than one type of graph. Compare and contrast the kinetic constants you obtain.
c. What is the turnover number?
d. What is the specific activity of the enzyme?
6. NMN adenyl transferase catalyzes the formation of NAD+ from NMN and ATP:
Unlock document

This preview shows page 1 of the document.
Unlock all 4 pages and 3 million more documents.

Already have an account? Log in

Get OneClass Grade+

Unlimited access to all notes and study guides.

Grade+All Inclusive
$10 USD/m
You will be charged $120 USD upfront and auto renewed at the end of each cycle. You may cancel anytime under Payment Settings. For more information, see our Terms and Privacy.
Payments are encrypted using 256-bit SSL. Powered by Stripe.