1. Fundamentals of Biochemistry
Fourth Edition
Donald Voet • Judith G. Voet • Charlotte W. Pratt
Chapter 4
Amino Acids
Copyright © 2013 by John Wiley & Sons, Inc. All rights reserved.

2. Chapter 4 Amino Acid Structure Key Concepts 4.1
• The 20 standard amino acids share a common structure but differ in their side chains. • Peptide bonds link amino acid residues in a polypeptide. • Some amino acid side chains contain ionizable groups whose pK values may vary.

3. General Structure of α-Amino Acid

4. Structures of Standard Amino Acids

5. Structures of Standard Amino Acids

6. Structures of Standard Amino Acids

7. Structures of Standard Amino Acids

8. Dipolar Amino Acid: Zwitterion

9. Condensation of Two Amino Acids

10. Nonpolar Side Chains

11. Uncharged Polar Side Chains

12. Cysteine Can Form Disulfide Bonds

13. Charged Polar Side Chains

14. Alanyltyrosylaspartylglycine
Ala-Tyr-Asp-Gly
AYDG

15. Amino Acid Nomenclature

16. Chapter 4 Amino Acid Structure Checkpoint 4.1
• Draw a generic amino acid and identify the  carbon and its substituents. • Draw the structures of the 20 standard amino acids and give their one- and three-letter abbreviations. • Draw a Cys–Gly–Asn tripeptide. Identify the peptide bond and the N- and C-termini, and determine the peptide’s net charge at neutral pH. • Classify the 20 standard amino acids by polarity, structure, type of functional group, and acid–base properties. • Why do the pK values of ionizable groups differ between free amino acids and amino acid residues in polypeptides?

17. Chapter 4 Stereochemistry Key Concepts 4.2
• Amino acids and many other biological compounds are chiral molecules whose configurations can be depicted by Fischer projections. • The amino acids in proteins all have the L stereochemical configuration.

18. Modified Amino Acids in Proteins

19. Biologically Active Amino Acid Derivatives

20. Dimerization of Glutathione