Amino Acids

For Manor's BICD 110 course (and Hui's BIBC 100 course lowk)

20 Standard Amino Acids

Three Groups

• Charged

• Polar

• Hydrophobic (Nonpolar)

  • Ignore special cases

Arginine (R)

• Positively Charged (Basic)

Lysine (K)

• Positively charged (Basic)

Histidine (H)

• Positively Charged (Basic)

• Side chain is ionizable at physiological pH (~7.4)

Aspartic Acid (D)

• Negatively Charged (Acidic)

• pKa = 3.7

Glutamic Acid (E)

• Negatively Charged (Acidic)

• pKa = 4.3

Serine (S)

Polar

Threonine (T)

• Polar

• Hydroxyl branch on side chain

Asparagine (N)

• Polar

• Amide group

Glutamine (Q)

• Polar

• Amide Group

Cysteine (C)

• Polar

• Sulfhydroxyl Group on side chain

Glycine (G)

• Aliphatic (Nonpolar)

• Only one Hydrogen as its side chain

Proline (P)

• Aliphatic (Nonpolar)

• Rigid ring strongly affects protein structure

Alanine (A)

Aliphatic (Nonpolar)

Valine (V)

Alpihatic (Nonpolar)

Isoleucine (I)

• Aliphatic (Nonpolar)

• Ile

• Same molecular weight as Leucine

Leucine (L)

• Aliphatic (Nonpolar)

• Leu

• Same molecular weight as Isoleucine

Methionine (M)

Aliphatic (Nonpolar)

Phenylalanine (F)

• Aromatic

  • Aliphatic (Nonpolar)

• Phe

Tyrosine (Y)

• Aromatic

  • Somewhat Polar, but classified as Aliphatic (Nonpolar)

• Tyr

Tryptophan (W)

• Aromatic

  • Aliphatic (Nonpolar)

• Trp

• Largest Amino Acid