zwitterionn.

1906 G. Mann Chem. Proteids vi. 210 Ions which are simultaneously electro-positive and electro-negative (Bredig), and which Küster calls ‘Zwitter-ions’, i.e. hermaphrodite-ions. Thus the ‘Zwitter-ion’ of glycocoll is the group H₃N—CH₂—COO.

1925 Jrnl. Chem. Soc. 127 i. 1381 The ‘isomeric change’ now takes the form of a fission of the molecule by the rupture of a bond, the final ionisation of which provides the electric charges which are needed to neutralise those already present in the ‘Zwitterion’.

1937 Nature 18 Sept. 492/1 One of the greatest advances in the understanding of the physico~chemical behaviour of amino-acids and proteins is due to the zwitterion theory introduced by Bjerrum in 1923.

1948 Endeavour 7 85/2 The products of [penicillin] inactivation are zwitter-ions.

1949 E. Chain in H. W. Florey et al. Antibiotics II. xxii. 847 The penicilloic acids are zwitterions with two acid groups and one basic group.

1968 D. W. Wood Princ. Animal Physiol. iii. 35 At the pH of living cells, lecithin forms a balanced zwitterion.

1982 R. M. Schultz in T. M. Devlin Textbk. Biochem. ii. 41 It is useful to calculate the exact pH at which an amino acid is electrically neutral and in its zwitterion form.

1946 Nature 16 Nov. 703/1 A hybrid structure derived from a number of ionic states of which there are..eight zwitterionic forms.

1949 E. P. Abraham & N. G. Heatley in H. W. Florey et al. Antibiotics I. ii. 94 These [substances]..may be neutral, acidic, basic, or zwitterionic.

1981 Biochimica et Biophysica Acta 668 117 Vesicles of zwitterionic phosphatidylcholine.