Download Amino Acids Worksheet and Problem Set

Amino Acids Workbook & Problem Set
Read Chapter 3 and complete the workbook as you go. Complete the problem set that
follows and show all work for full credit. This Workbook and Problem set is due no later
than 3AM the night of September 14th (morning of 9/15/12).
Chapter 3.1:
Draw a generic version of an amino acid and label each part:
Define the term Steriochemistry:
Define the term Chiral:
Draw Glyceraldehyde, show the L- and D- versions and explain what the L and D
designations mean.
Chapter 3.2:
What does the R group determine for an amino acid and why is it important?
Which are the aliphatic amino acids? (Group 1)
Which are the Group 2 amino acids and why?
Which are the Group 3 amino acids and why?
Which are the Group 4 amino acids and why?
Chapter 3.3:
Draw the normal structure of a generic amino acid at physiological pH:
Define the term Zwitterion:
Explain the relationship between the pH of a system and the charge on an amino acid.
Using aspartic acid, describe what pH changes would need to take place to go from a
fully protonated structure to a fully unprotonated structure.
Chapter 3.4:
Use Aspartic Acid and Leucine and form a peptide bond between them:
Using the structure above show how the peptide bond can have resonance:
Chapter 3.5: N/A Do not need to read
Problem Set:
1. For each of the 20 common amino acids:
a. Draw “3-D” Lewis Structures
b. Highlight any formal groups capable of protonation.
c. For each of the groups in part b, look up and label their pK a values.
d. Label each structure with both its one letter and 3 letter designation.
e. Determine if the amino acid is polar or non-polar and mark it P or NP,
respectively.
2. Using an appropriate amino acid, draw a disulfide bond structure.
3. Draw the following polypeptides and determine their pI
a.
b.
c.
d.
FINAL
LIVE
HEAD
RATFINK
4. What is the D,L system of nomenclature? What is the R,S system of
nomenclature? Why are these systems necessary? Explain.
5. Draw an appropriate titration curve for aspartic acid, labeling the axes and
indicating the equivalence points and the pKa values.