C00 C00 C00 *H3N-H +H3N-H *H3N-H H CH3 CH(CH3)2 Glycine(Gly) Alanine (Ala) Valine (Val) 甘氨酸 丙氨酸 缬氨酸 coO C00 C00 *H3N-H +H3N-H 肽 CH2 CH(CH3) +H2N CH(CH3)2 CH2CH3 骨架 Leucine (Leu) Isoleucine (Ile) 化 Proline (Pro) 亮氨酸 异亮氨酸 脯氨酸