20 Most Common Amino Acids in Proteins

Question 1

Charged (side chains often make salt bridges)

Answer 1

• Arginine - Arg
• Lysine - Lys
• Aspartic acid - Asp
• Glutamic acid - Glu

Question 2

Polar (usually participate in hydrogen bonds as proton donors or acceptors)

Answer 2

• Glutamine - Gln - Q
• Asparagine - Agn - N
• Histidine - His - H
• Serine - Ser - S
• Threonine - Thr - T
• Tyrosine - Tyr - Y
• Cysteine - Cys - C
• Methionine - Met - M
• Tryptophan - Trp - W

Question 3

Hydrophobic (normally buried inside the protein core)

Answer 3

• Alanine - Ala - A
• Isoleucine - Ile - I
• Leucine - Leu - L
• Phenylalanine - Phe - F
• Valine - Val - V
• Proline - Pro - P
• Glycine - Gly - G