COO HaN- C-H HaN- C-H CHa CH CHs CHa Alanine Valine 非极性氨基酸8 COO COO H:N- C一H HgN- C-H -H CH3 CH 2 CH2 CH3CH3 CH3 Leucine Methionine Isoleucine COO COO C00- H一 C-H C HyN- -H H2N CH2 CH H2C CH2 NH Phenylalanine Proline Tryptophan 非极性氨基酸8