Chemical Modification of Purified Diphtheria Toxin

[摘要] Purified diphtheria toxin may be completely modified to toxoid, without altering the combining properties, by treatment with an excess of formaldehyde in an acid solution or with very low concentrations of formaldehyde in an alkaline solution. Higher concentrations of formaldehyde in alkaline solution cause impairment of the flocculating, combining, and immunizing properties of the resulting toxoid.Hexamethylenetetramine produces unaltered toxoid from purified toxin at any pH between 6.0 and 9.0.The relation of these findings to the rôle of amino compounds such as peptone in toxoid formation, as postulated by previous investigators, is discussed.Purified diphtheria toxin has a specific optical rotation (α25° D ) of approximately −45°. This is not appreciably changed by modification to toxoid.In diphtheria toxin the amino nitrogen constitutes about 14 per cent of the total nitrogen. This is unusually high for a protein. After modification to toxoid with formaldehyde about 30 per cent of the amino nitrogen is selectively and irreversibly bound and the protein acquires an increased stability to denaturation. The possible mechanism of these chemical changes and their relation to the specific modification of the toxic property is discussed.

[学科分类] 生物科学（综合）