Learn: 20 Amino Acids

Glycine (Gly, G)

Nonpolar, aliphatic

Smallest AA, achiral

Alanine (Ala, A)

nonpolar, aliphatic

Valine (Val, V)

nonpolar, aliphatic

Leucine (Leu, L)

Nonpolar, Aliphatic

Isoleucine (Ile, I)

Nonpolar, aliphatic

Methionine (Met, M)

Nonpolar, aliphatic

One of two AAs that contains a sulfur atom in the side chain; because S has a methyl group attached, it's considered to be relatively nonpolar

Proline (Pro, P)

Nonpolar, aliphatic

Cyclic amino acid; introduces kinks in the Alpha helix (rarely found in a-helices except those that cross the cell membrane) and turns in Beta-pleated sheets

Tryptophan (Trp, W)

Nonpolar, aromatic

Phenylalanine (Phe, F)

Aromatic, Nonpolar

Tyrosine (Tyr, Y)

Aromatic, Relatively polar (bc of -OH)

Serine (Ser, S)

Polar, uncharged

-OH group makes this highly polar due to Hydrogen bonding capabilities

Threonine (Thr, T)

Polar, uncharged

-OH group makes this highly polar due to Hydrogen bonding capabilities

Asparagine (Asn, N)

Polar, uncharged

Amide side chain whose N doesn't gain or lose hydrogen, does not become charged

Glutamine (Gln, Q)

Polar, uncharged

Amide side chain whose N doesn't gain or lose Hydrogen, does not become charged

Cysteine (Cys, C)

Polar, uncharged

Has (-SH)/thiol group, prone to oxidation because sulfur is larger and less electronegative than O-H bond (SH bond weaker than OH bond).

2 Cysteine molecules can oxidize to form cystine (disulfide bond), creating loops in the protein chain

Aspartate (Asp, D)

Negatively charged, Acidic side chain

Aspartic acid is the protonated form

Glutamate (Glu, E)

Negatively charged, Acidic side chain

Glutamic acid is the protonated form

Arginine Arg, R

Positively charged, Basic side chain

3N - positive charge delocalized over all three

Lysine (Lys, K)

Positively charged, Basic side chain

Terminal primary amino group

Histidine (His, H)

Positively charged, basic side chain

Imidazole-aromatic ring with 2N atoms