20 Commonly Occuring Amino Acids

Front 1

Amino Acids with Aliphatic Side Chains

Back 1

Valine, Leucine, Isoleucine, Methionine (hydrophobic, often found in the center of ptns away from water)

Front 2

Glycine

Back 2

Side Chain: H
Most structurally permissible aa

Front 3

Proline

Back 3

Side Chain: ring, attached to N back bone
Most structurally restrictive aa

Front 4

Aromatic Amino Acids (list them)

Back 4

Phenylalanine, Tyrosine, Tryptophan ( Tyr and Trp absorb UV light, these side chains are considered hydrophobic but both Tyr and Tp have functional groups that can do polar h-bonding activity).

Front 5

Amino Acids with Hydroxyl Groups (-OH)

Back 5

Serine, Threonine (These side chains are polar, often involved in H bonding)

Front 6

Cysteine

Back 6

able to form disulfide bonds ( hair relaxer), reduced thiol group can also funxn as a ligand for a metal ion like Zn2+

Front 7

Basic Amino Acids

Back 7

Lysine, Arginine, Histidine (lys and arg will be positive at neutral pH)
Often form salt bridges with neg. groups

Front 8

Carboxylates (-COOH)

Back 8

Aspartate, Glutamate (neg at neutral pH)

Front 9

Carboyamides

Back 9

Asparagine (Asn), Glutamine (Gln)
Polar Amino Acids (not charged at neutral pH)