20Aimoac ALIPHATIC AMINO AC IDS CH。CH 3/ CH CH2一CH c00 H。N一C-C00 c00 c00 H H H H Glycine(Gly)G Alanine(Ala)A valine(val)V Leucine(Leu)L Isoleucine(e)I AMINO ACIDS WITH HYDROXYL-OR SULFUR-CONTAIN ING SIDE CHAINS CH CYCLIC AMINO ACID HCOH H.N-C-COO CoO- H H Serine(Ser)S Cysteine(Cys)C Threonine(Thr)T Methionine(Met)M Proline(Pro)P20Aimoac id