Lecture Notes: Amino Acids and Protein Structure at the Amino Animal Zoo

Introduction to Sketchy

• Sketchy turns complex concepts into memorable visual stories.
• Focus on protein, amino acids, and their structure.

Basic Structure of Amino Acids

• Components: Carboxylic acid group, amino group, unique side chain, alpha carbon.
• Stereoisomer Form: Humans have L-stereoisomer form of amino acids.
• Peptide Bonds: Join amino acids to form polypeptides.

Major Classes of Amino Acids

• Nonpolar Amino Acids: Hydrophobic.
  • Represented in a desert exhibit.
  • Examples: Glycine, Alanine, Leucine, Isoleucine, Valine, Methionine, Proline, Tryptophan, Phenylalanine.
  • Glycine: Smallest, flexible, used in collagen, purine synthesis.
  • Alanine: Gluconeogenesis substrate.
  • Methionine: Sulfur-containing, precursor to SAM and cysteine.
  • Proline: Has a five-membered ring, found in collagen.
  • Tryptophan & Phenylalanine: Aromatic, precursors to other compounds.

Polar Amino Acids

• Characteristics: Uneven charge distribution.
• Represented in North Pole Exhibit:
  • Examples: Tyrosine, Threonine, Asparagine, Serine, Cysteine, Glutamine.
  • Tyrosine: Aromatic, precursor to melanin and catecholamines.
  • Serine & Threonine: Undergo post-translational modifications.
  • Cysteine: Forms disulfide bridges to stabilize proteins.

Acidic Amino Acids

• Examples: Glutamate, Aspartate.
• Characteristics: Negative charge at body pH, hydrophilic.

Basic Amino Acids

• Examples: Arginine, Lysine, Histidine.
• Characteristics: Positive charge, interact with DNA (e.g., in histones).
• Function: Important for growth and cellular processes.

Essential Amino Acids

• Cannot be synthesized by the body.
• Examples: Threonine, Methionine, Tryptophan, Phenylalanine, Leucine, Isoleucine, Valine, Histidine, Lysine.

Metabolism: Glucogenic vs. Ketogenic Amino Acids

• Glucogenic: Metabolized to glucose.
• Ketogenic: Converted to acetyl-CoA, not glucose.
  • Strictly Ketogenic: Leucine, Lysine.
  • Both: Threonine, Tyrosine, Tryptophan, Phenylalanine, Isoleucine.

Conclusion

• Nonpolar: Glycine, Alanine, Leucine, Isoleucine, Valine, Methionine, Proline, Tryptophan, Phenylalanine.
• Polar: Tyrosine, Threonine, Asparagine, Serine, Cysteine, Glutamine.
• Acidic: Aspartate, Glutamate.
• Basic: Arginine, Lysine, Histidine.

Note: This lecture used a zoo metaphor to aid in memorizing the characteristics and functions of different amino acids.