Lecture Notes: Amino Acids in Medical School

Key Concepts

• Amino Acids: Building blocks of proteins and metabolic intermediates.
  • Role: Cofactors in biochemical reactions, deriving important end products.
• Categories of Amino Acids: Essential knowledge for exams.

Essential vs. Non-essential Amino Acids

• Essential Amino Acids: Must be obtained through diet (cannot be produced by the body).
  • Examples: Threonine, Tyrosine, Valine, Phenylalanine, Isoleucine, Leucine, Lysine, Methionine, Histidine.
• Non-essential Amino Acids: Can be synthesized by the body.

Acidic vs. Basic Amino Acids

• Acidic Amino Acids:
  • Aspartic acid, Glutamic acid.
• Basic Amino Acids:
  • Histidine, Lysine, Arginine.
  • Mnemonic: "Her Leggings Are Basic" (H for Histidine, L for Lysine, A for Arginine).

Ketogenic, Glucogenic, and Mixed Amino Acids

• Ketogenic:
  • Leucine, Lysine (Mnemonic: "Lamb and Liver").
• Glucogenic:
  • Histidine, Methionine, Valine (Mnemonic: "Honey Mango Vanilla").
• Mixed (Keto and Glucogenic):
  • Isoleucine, Threonine, Tyrosine, Phenylalanine.

Amino Acid Derivatives

Phenylalanine

• Converts to Tyrosine, then Dopa, leading to Dopamine, Norepinephrine, Epinephrine (Catecholamines).

Tryptophan

• Derivatives: Niacin (leads to NAD+ and NADP+), Serotonin (leads to Melatonin).
  • Related Disease: Hartnup Disease (decreased resorption of tryptophan in kidneys, leads to Niacin deficiency symptoms).

Histidine

• Converts to Histamine (Vitamin B6 cofactor).

Glycine

• Converts to Porphyrin (used to generate Heme).

Glutamate

• Converts to GABA and Glutathione.

Arginine

• Derivatives: Creatine, Urea, Nitric Oxide.

Branched Chain Amino Acids (BCAAs)

• Isoleucine, Leucine, Valine:
  • Broken down by Branched Chain Alpha-Keto Acid Dehydrogenase.
  • Related Disease: Maple Syrup Urine Disease (deficiency of enzyme leads to symptoms like syrup-smelling urine, intellectual disability).
  • Mnemonic: "I Love Vermont Maple Syrup Can I Have a Sip" (I for Isoleucine, L for Leucine, V for Valine, SIP for Symptoms: Syrup-smelling urine, Intellectual disability, Poor oral intake).

Summary

• High-yield topics include amino acid categories, derivatives, and related diseases (Hartnup and Maple Syrup Urine Disease).
• Mnemonics and understanding of biochemical pathways are essential for exam preparation.