Habersetzer-Rochat C, Sampieri F
Biochemistry. 1976 Jun 1;15(11):2254-61. doi: 10.1021/bi00656a002.
Chemical modification of some trifunctional amino acid residues in toxins I, II, and III of the scorpion Androctonus australis Hector have been performed. The results indicate: (1) Reduction and methylation of one disulfide bridge destroy toxic activity of toxin II. (2) The only tryptophan residue of toxin II (position 38) is not included in the active site of the molecule. (3) Modification of five carboxylates out of the seven contained in toxin II suppresses the toxic activity. (4) Acetylation of the lysine and tyrosine residues in toxin II leads to the loss of both toxic and antigenic activity. Treatment of the acetylated toxin by hydroxylamine restores partially the antigenic activity. In the case of toxin I, total acetylation abolishes only the toxic activity. It is concluded that at least one tyrosine residue must be involved in an antigenic site of toxin II. (5) Citraconylation of toxins II and III leads to complete loss of toxicity; decitraconylation restores full activity. (6) Guanidination of toxin II does not affect its toxicity significantly. (7) Alkylation of toxin II by iodoacetic acid affects both amino groups and histidine residues. The loss of toxicity is mainly due to the modification of the lysine residues. In the case of toxin I, the kinetics of toxicity loss closely parallel the covalent modification of one lysine residue.
对澳大利亚杀人蝎（Androctonus australis Hector）毒素I、II和III中的一些三官能氨基酸残基进行了化学修饰。结果表明：（1）一个二硫键的还原和甲基化破坏了毒素II的毒性活性。（2）毒素II唯一的色氨酸残基（第38位）不包含在分子的活性位点中。（3）毒素II所含七个羧酸盐中的五个羧酸盐的修饰抑制了毒性活性。（4）毒素II中赖氨酸和酪氨酸残基的乙酰化导致毒性和抗原活性均丧失。用羟胺处理乙酰化毒素可部分恢复抗原活性。就毒素I而言，完全乙酰化仅消除毒性活性。得出的结论是，至少一个酪氨酸残基必须参与毒素II的抗原位点。（5）毒素II和III的柠康酰化导致毒性完全丧失；脱柠康酰化恢复全部活性。（6）毒素II的胍基化对其毒性没有显著影响。（7）碘乙酸对毒素II的烷基化作用影响氨基和组氨酸残基。毒性丧失主要归因于赖氨酸残基的修饰。就毒素I而言，毒性丧失的动力学与一个赖氨酸残基的共价修饰密切平行。
