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help with this chem question: A and B have the following pI values: Protein A ;p

ID: 784441 • Letter: H

Question

help with this chem question:

A and B have the following pI values:

Protein A   ;pI value 6.2

Protein B   ; pI value 7.3

         You want to use a phosphate buffer at pH 7.0 separate proteins by ion exchange.

1a)Is it possible to separatre A and B under these buffer conditions? Why or why not?   What type of ion exchnage resin (cation or anion) would you use?

1b)DRAW a column profile for the separation using the resin you chose.Be sure to indicate where each of the protiens elutes on the profile?

1c)Deduce the 4th structure of A and B based on the SDS-IMAGE gel"


      STDS    PROTEIN A   PROTEIN B

97  ____

68  ____

                   ____

43  ____

                   ____

26  ____

                                   ____

14  ____

, assuming the MW values for protein A=160000MW and B=60000 MW.Explain your conculsions based on the details of the SEPARATION method.

Is it possible that either protein has any identical subunits?  

If so, how might you determine if that is the case?

Explanation / Answer

Ion exchange chromatography separates compounds according to the nature and degree of their ionic charge.
The column to be used is selected according to its type and strength of charge.
Anion exchange resins have a positive charge and are used to retain and separate negatively charged compounds,
while cation exchange resins have a negative charge and are used to separate positively charged molecules.

since pI1 is more deviatated from buffer solution pH , negative charges will be stronger in this case so, we will use cation exchage resin