Chapter 6, Problem 6.34P

Interpretation Introduction

Interpretation:

Whether the amino acid glycine will migrate toward anode or cathode in an electrophoresis is to be explained.

Concept introduction:

Isoelectric point (pI) or isoelectric pH is the pH at which the substance has zero charge. An amino acid’s pI is the average of its two pKa values.

If the pH of the solution is higher than the pI, the substance will deprotonate carrying negative charge. Conversely, if the pH is lower than the pI, the substance will be protonated and will carry a positive charge.

Any ion that has net positive charge (cations) will migrate toward the negatively charged terminal i.e. cathode, and the ion with negative charge (anions) will migrate toward positively charged terminal i.e. anode.