1. The isoelectric point, pI, is the pH at which the overall charge on the protein is zero. At a pH below pI, the protein will become positively charged overall.

At a pH above pI, the protein will become negatively charged overall.

(i) Explain what happens to BSA (pI=4.7) if a loading buffer of pH 7 is used, followed by an eluting buffer of pH 11.

Discuss the charges on BSA and DEAE at the two pH's.

Include whether the protein binds or elutes.

(ii) Explain what happens to BSA (pI=4.7) if a loading buffer of pH 7 is used, followed by an eluting buffer of pH 3.5.

Give the charges on BSA and DEAE at the two pH's.

Include whether the protein binds or elutes.

(iii) Explain what happens to BSA (pI=4.7) if a loading buffer of pH 11 is used.

Give the charges on BSA and DEAE at this pH.

Include whether the protein binds or elutes.