Wada K, Ozaki Y, Matsubara H, Yoshizumi H
J Biochem. 1982 Jan;91(1):257-63. doi: 10.1093/oxfordjournals.jbchem.a133683.
Purothionin from wheat flour was chemically modified by acetic or succinic anhydride under specific conditions. The complete modification of all amino groups of purothionin caused a large change in the net charge of the molecule, leading to the loss of the toxicity to mice and yeast. The sole tyrosyl residue in purothionin was nitrated by tetranitromethane at neutral pH or iodinated by the lactoperoxidase method. The nitro- and diiodo-derivatives of purothionin showed considerably reduced toxicity. Based on these modification studies we conclude that the positive charges of lysyl residues have an important role in the interaction with the negatively charged cell surface, and that the emergence of the toxicity of purothionin depends on a certain state of the tyrosyl residue.
在特定条件下，用乙酸酐或琥珀酸酐对小麦粉中的硫堇进行化学修饰。硫堇所有氨基的完全修饰导致分子净电荷发生很大变化，从而使其对小鼠和酵母的毒性丧失。在中性pH条件下，用四硝基甲烷对硫堇中唯一的酪氨酸残基进行硝化，或用乳过氧化物酶法进行碘化。硫堇的硝基和二碘衍生物的毒性显著降低。基于这些修饰研究，我们得出结论，赖氨酸残基的正电荷在与带负电荷的细胞表面相互作用中起重要作用，并且硫堇毒性的产生取决于酪氨酸残基的某种状态。
