Nonpolar,aliphatie R groups Aromatic R groups C00 C00 C00 C00 c00 C00 HNC-H HNC-H HNC-H HN-C-H HN一CH HNC-H 宜 C CH CH CH. CH CH CH C-CH Glycine Alanine Valine NH C00 C00 C00 OH HN-C-H HNC-H HN-C-H Phenylalanine Tyrosine Tryptophan CH2 H-C-CH CH CH CH, CH.CH, CH Positively charged R groups CH C00 C00 C00 Leucine Methionine Isoleucine HN-C-H HN-C-H HN-C-H CH2 CH, CH: Polar,uncharged R groups CH: CH: C-NH C00 C00 C00 CH CH2 CH HNC-H HN C-H HN-C-H CH2 NH CH OH H-C-OH CHa NH C-NHa CH3 SH NH Structural Serine Threonine Cysteine Lysine Arginine Histidine formula of 00 C00 C00 Negatively charged R groups - HN-C-H HN-CH C00 C00 the standard CH2 CH CH. HN-C-H HN-C-H H.C- 一CH amino acids CH. CH CHa C00 CH2 (L5-5) C00 Proline Asparagine Glutamine Aspartate GlutamateStructural formula of the standard amino acids (L5-5)