2. Casein molecules in milk have some glutamic acid residues that change their charge based on the pH of their surroundings. This is one factor why the proteins misfold and aggregate when you add vinegar to warm milk. Glutamate is the conjugate base for glutamic acid, and forms when the carboxyl group of glutamic acid loses a proton: COOHCOO+H+ The pKa of this reaction is 4.0. In solution glutamic acid is in rapid equilibrium, so we can think of the species as having a relative charge between 0 and 1. Use MATLAB or Excel to plot the relative charge of glutamic acid as a function of pH. (Ignore the N - and C-termini of the amino acid.) Note that the Henderson-Hasselbach equation is a ratio of [base]/[acid], and we want relative charge here ([base]/[total]). The molecule will be in either acid or base form, so for a population of molecules: [ base ]+[ acid] ]=[ total ]