Chapter 6, Problem 6.74P

Interpretation Introduction

Interpretation

The Isoelectric point (pI) of tyrosine is to be calculated. In an electrophoresis experiment, will tyrosine migrate at a $\text{pH = 7}$, and the terminal to which it will migrate is to be determined.

Concept introduction:

Electrophoresis is a common way of separating a mixture of amino acid. In electrophoresis, any ion that has a net positive charge, at that pH, will migrate toward the negatively charged terminal whereas any ion having a net negative charge will migrate toward the positively charged terminal.

An amino acid’s pI is the average of its two pKa values associated with the zwitterion- the pKa value corresponding to the proton transfer reaction in which the zwitterion is a product, and the pKa value corresponding to the proton transfer reaction in which the zwitterion is a reactant.