Below is a chart of pI (Isoelectric Point) and molecular weight of four proteins
ID: 59574 • Letter: B
Question
Below is a chart of pI (Isoelectric Point) and molecular weight of four proteins:
Protein
Molecular Weight (kDa)
pI
Histone H3
15
11.1
Myoglobin
17
7.2
BSA
68
4.7
Myosin
200
5.2
A. Cation exchange chromatography uses negative charges to retain positively charged proteins. You run a mixture of the proteins above on a cation exchange column at pH = 7.2. What proteins will be retained?
B. What sequence do you expect the mixture of proteins to elute (first to last) when you run the mixture on a size exclusion column?
C. If you run the mixture on an SDS page, which protein will migrate most rapidly in the gel? Which one most slowly?
D. Native PAGE works similarly to SDS PAGE except that proteins are kept under non-denaturing conditions so that the proteins’ secondary structure and native charges are maintained. If you run the mixture above on a native PAGE with buffers at pH = 7.2, which direction will these proteins migrate towards- the positive pole (anode) or the negative pole (cathode)- when an electrical current is applied?
Protein
Molecular Weight (kDa)
pI
Histone H3
15
11.1
Myoglobin
17
7.2
BSA
68
4.7
Myosin
200
5.2
Explanation / Answer
A) In cation exchange the positively charged proteins bind to the negatively charged stationary phase
Myosine histone H3 retaines BSA and myosin elute in the wash becausse isoelectric point is high in myosin and histone H3
B) Size exclusion colum run based on molecular size
HistoneH3, myoglobin BSA, Myosin (histoneH3 size is small it elut 1st , myosin siz is big so elut last)
C) SDS phase based on molecular weight big weight molecule move slowly ,smaller molecular weight move rapidly
Histone H3 move rapidly, myosin move slowly because histoneH3 weight is less, myosin weight is high
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.