The following question are based on the following proteins. a. list the proteins
ID: 526517 • Letter: T
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The following question are based on the following proteins. a. list the proteins in the order of first to the last that eluted out from a size exclusion column b. list the proteins in the order of first to the last that eluted out from a cation exchanger column c. Predict the relative position of the proteins if they are subjected to SDS-PAGE in the following figure d. Draw relative positions of the proteins after the mixture of the four proteins applied to two dimensional gel electrophoresis: isoelectric focusing is applied in the x axis; SDS-PAGE is applied in the y-axis.Explanation / Answer
1. a) Remember that in size exclusion chromatography, the higher its Mr, the faster the elution. With that in mind we can order the proteins as follow:
A, C, D, B
Where A is the first eluted because it has the highest Mr and B is the last eluted because it has the lowest Mr.
b) Remember that in cation exchange chromatography, the lower the pH, the faster the elution. With that we can predict the following order:
A, D, C, B
Where A is eluted first because it has the lowest pH and B is eluted last because it has the highest pH.
c) In SDS-PAGe the mobility of the molecules is indirectly proportional to the size (Mr), so the order in the figure would be:
A, C, D, B
Where B is the smallest molecule (and thus travels the farthest) while A is the biggest (and thus travels the least).
d) If we focus on isoelectric point the molecules are placed on it in the diagram, meaning you would place A at pH 3, B at pH 9, C at pH 5 and D at pH 5.
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