Zwitterion an ion with both a positive and a negative charge . amino acids and form zwitterions : the amino group has the form - nh3 + and the acid group is ionized as - coo - 两性离子：既带有正电荷又带有负电荷的离子。氨基酸就是这样一种离子：氨基基团为- nh3 +而羧基端为- coo - 。
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Ni xiangshan * , shi xiufan , lin lunjiang * 1988 an interaction potential between an alanine zwitterion and a water molecule based on abainitio calculations . international journal of quantum chemistry , 34 : 527 - 533 倪向善* 、石秀凡、林伦奖* 1988基于从头算的丙氨酸两性离子和水分子的相互作用。国际量子化学杂志, 34 : 521 533 。
