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目的：建立一种测定ＮＡＤａｓｅ细菌毒素活性的非放射性测定法。方法：建立一个ＮＡＤ（辅酶Ｉ）依赖的显色系统，在该系统中，ＮＡＤ接受乳酸脱氢酶（ＬＤＨ）从乳酸脱下来的氢，再通过ＰＭＳ（吩嗪二甲酯硫酸盐）传递给ＩＮＴ（碘化硝基四氮唑蓝），使后者还原而显色。如果ＮＡＤａｓｅ毒素分解ＮＡＤ，就会打断递氢链而抑制显色反应。结果：显色系统中，ＮＡＤ含量与显色有良好线性关系（Ｒ＝０．９８９８）。绿脓杆菌外毒素Ａ分解ＮＡＤ而抑制显色反应。以毒素含量为自变量，以毒素对显色反应的抑制为应变量，建立了对数线性回归方程Ｙ＝１２．５Ｘ０．２６，当Ｙ＝５０％时［即显色系统中的ＮＡＤ有半数（２５０ｎｇ）被分解］，Ｘ＝２０７（ｎｇ）。定义分解１ｎｇＮＡＤ的毒素活性为一个单位，则２０７ｎｇ毒素含有２５０个毒素活性单位。该方法的测定敏感性达到“ｎｇ”水平。结论：本方法是一种敏感的测定ＮＡＤａｓｅ细菌毒素活性的非放射性测定方法。
Objective: To establish a non-radioactive assay for measuring the activity of NADase bacterial toxins. Methods: A NAD (coenzyme I) -dependent colorimetric system was established in which NAD received hydrogen removed from lactate by lactate dehydrogenase (LDH) and passed to PMS (phenazine dimethyl sulfate) INT (Nitroblue tetrazolium iodide), the latter reduction and color. If NADase toxin decomposes NAD, it will interrupt the hydrogen transfer chain and inhibit the color reaction. Results: There was a good linear relationship between the content of NAD and color in the color system (R = 0.9898). Pseudomonas aeruginosa exotoxin A decomposes NAD and inhibits the color reaction. Taking the toxin content as the independent variable and the inhibition of the chromogenic reaction toxins as the dependent variable, a logarithmic linear regression equation Y = 12.5X0.26 was established. When Y = 50% [ie, half of the NAD in the chromogenic system (250 ng) is decomposed], X = 207 (ng). To define a toxin that breaks down 1 ng of NAD as one unit, 207 ng of toxin contains 250 toxin units of activity. The sensitivity of this method reaches “ng” level. Conclusion: This method is a sensitive non-radioactive assay for measuring the activity of NADase bacterial toxins.