What solution conditions are required for a protein to be a positively charged macroion?
A)pH of solution is greater than the protein's pI
B)pH of solution is less than the protein's pI
C)pH of solution is greater than the protein's pI and ionic strength is low
D)pH of solution is less than the protein's pI and ionic strength is low
E)none of the above

Question

Quizplus · Accepted Answer

Proteins can carry a net positive charge only if the pH of the solution is less than their pI. At a lower pH, the protein will have an excess of protons, which causes it to become positively charged. The opposite is true for a negatively charged macroion. At a pH greater than the protein's pI value, the protein will have an excess of negative charges, making it negatively charged. The ionic strength of the solution does not affect the charge of a protein but may affect the protein stability and activity.

What Solution Conditions Are Required for a Protein to Be