MCAT Biochemistry Master Study Guide
, MCAT Biochem: Amino Acids & Proteins
Must knows
● For each amino acid, you MUST know the structure, classification (e.g. nonpolar), pka values of
R groups, and 3 letter/1 letter abbreviation
● Proteins in the human body use L-amino acids (all S configuration, except cysteine); at
physiological pH, carboxylic acids are deprotonated and amino groups are protonated.
Nonpolar, Nonaromatic Amino Acids
● These are hydrophobic and typically found in the interior of proteins
● Mnemonic: "Grandma Always Visits Lisbon In March For William’s Party”
Glycine (Gly, G) Alanine (Ala, A) Valine (Val, V)
smallest AA, achiral, nitrogen metabolism branched chain AA
flexible
Leucine (Leu, L) Isoleucine (Ile, I) Methionine (Met, M)
branched chain AA branched chain AA sulfur containing, encoded by AUG
Phenylalanine (Phe, F) Tryptophan (Trp, W) Proline (Pro, P)
absorbs UV, aromatic absorbs UV, aromatic, indole secondary amine, helix breaker
Acidic Amino Acids
Aspartic Acid (Asp, D) Glutamic Acid (Glu, E)
hydrophilic, pKa = 4 hydrophilic, pKa = 4
, MCAT Biochem: Amino Acids & Proteins
Must knows
● For each amino acid, you MUST know the structure, classification (e.g. nonpolar), pka values of
R groups, and 3 letter/1 letter abbreviation
● Proteins in the human body use L-amino acids (all S configuration, except cysteine); at
physiological pH, carboxylic acids are deprotonated and amino groups are protonated.
Nonpolar, Nonaromatic Amino Acids
● These are hydrophobic and typically found in the interior of proteins
● Mnemonic: "Grandma Always Visits Lisbon In March For William’s Party”
Glycine (Gly, G) Alanine (Ala, A) Valine (Val, V)
smallest AA, achiral, nitrogen metabolism branched chain AA
flexible
Leucine (Leu, L) Isoleucine (Ile, I) Methionine (Met, M)
branched chain AA branched chain AA sulfur containing, encoded by AUG
Phenylalanine (Phe, F) Tryptophan (Trp, W) Proline (Pro, P)
absorbs UV, aromatic absorbs UV, aromatic, indole secondary amine, helix breaker
Acidic Amino Acids
Aspartic Acid (Asp, D) Glutamic Acid (Glu, E)
hydrophilic, pKa = 4 hydrophilic, pKa = 4
