coo coo coo +H3N-H +H3N- H +H3N-H CH2OH CHOH CH3 CH2SH Serine(Ser) Threonine(Thr) Cysteine(Cys) 丝氨酸 苏氨酸 半胱氨酸 coo c00 cOO +H3N-H +H3N- 一H *H3N-H CH2 CH2 CH2 CH2SCH3 CONH2 CH2 CONH2 Methionine (Met) Asparagine (Asn) Glutamine(GIn) 甲硫氨酸（蛋氨酸) 门冬酰胺 谷氨酰胺