On the Heat Stability of the Diphtheria Toxin

[摘要] The property of heat sensitiveness is considered as a characteristic of bacterial exotoxins. In a previous paper (2), however, we have pointed out that a part of the scarlatinal toxin could stand boiling for thirty minutes. It seems rather curious that the scarlatinal toxin is an exception to this general rule. In order to analyse this general rule—heat sensitiveness of exotoxins—we examined carefully the heat stability of the diphtheria toxin as a typical exotoxin and found that a part of the diphtheria toxin also could stand boiling for thirty minutes.Five portions of diphtheria toxin No. 166 (pH 8.5; m.l.d. = 1/300 cc.) heated to varying temperatures (60°, 70°, 80°, 90°, and 100°C.) for thirty minutes were tested for their m.r.d. on two guinea pigs and it was found that the ratio of m.r.d. of the heated toxins and that of unheated control was 50 (60°C.), 500 (70°C.), 2,000 (80°C.), 10,000 (90°C.) and 10,000 (100°C.) respectively.

[学科分类] 生物科学（综合）