Learning Goals/Objectives for Chapter 2A:  After class and this reading, students will be able to

• state the charge on amino acid side chains using the Henderson Hasselbach equation and the approximate charge by inspection at any given pH
• draw mechanisms and identify products for the reaction of nucleophilic side chains Lys and Cys with common chemical modification agents and extend this understanding to reactions of His.
• draw mechanisms for disulfide exchange reactions for sulfhydryls using them and oxidation numbers to explain redox reactions of cysteine/cystine.