Coo Coo Coo thrN H *H3N-H CH2OH CHOH H CH2SH Serine (ser) Threonine(thr Cysteine(Cys) 丝氨酸 苏氨酸 半胱氨酸 COo COo Coo +H3 N--H H2N H H3N H CH CH 2 CH H2SCH3 CONH CH CONH Methionine met Asparagine(Asn) Glutamine(Gln) 甲硫氨酸(蛋氨酸) 门冬酰胺 谷氨酰胺