Need help specifically with the stereochemistry.

3. Insulin is a multipeptide hormone that is released in response to high blood glucose levels thereby regulating the metabolism of carbohydrates, fats, and proteins. Shown below a ribbon representation of the 3D structure as well as a pictorial representation of the primary sequence (PDB = 1trz). Answer the following questions about this peptide. [30 pts.] a) Draw the chemical structure of the last eight amino acids in the B chain in the correct protonation state. \{Note: Make sure not to ignore stereochemistry.\} b) Of the amino acids you drew in part a, identify the most acidic side chain and calculate the protonation state (\% protonated, \% deprotonated) at a physiologically relevant pH. c) Of the amino acids you drew in part a, identify the most basic side chain and calculate the protonation state (\% protonated, \% deprotonated) at a physiologically relevant pH