Martins V S, Triboni E R, Bonilha J B S, Gonçalves L M, Mortara L, Carvalho L A C, Manda B R, Lacerda C D, Meotti F C, Politi M J, Chaimovich H, Cuccovia I M
Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Brazil.
Escola de Engenharia de Lorena da Universidade de São Paulo, Departamento de Engenharia Química (DEQUI), Lorena, SP, Brazil.
Heliyon. 2020 Sep 16;6(9):e04938. doi: 10.1016/j.heliyon.2020.e04938. eCollection 2020 Sep.
The aromatic nucleophilic substitution reactions of the nitro group of 4-Nitro--alkyl-1,8-naphthalimides by thiolate anions produce fluorescent derivatives and their rates are strongly accelerated by micelles of hexadecyltrimethylammonium chloride even at low pH. Acceleration factors of this reactions can reach million-fold. As the products are oxidant-insensible, this reaction allows the determination of SH- containing compounds such as cysteine, glutathione or proteins even in oxidative conditions. Limits of detection are as low as 5 × 10 M, ten times lower than the limit for the classic 5,5'-dithiobis-(2-nitrobenzoic) acid method. Moreover, this reaction can be developed at pHs between 6.5 and 7.5 thereby diminishing the rate of spontaneous oxidation of the thiols. In addition, we demonstrated that 4-Nitro--alkyl-1,8-naphthalimides can be used to evidence SH groups in peptides, proteins and living cells.
硫醇盐阴离子对4-硝基-α-烷基-1,8-萘二甲酰亚胺的硝基进行芳环亲核取代反应可生成荧光衍生物，即使在低pH值下，十六烷基三甲基氯化铵胶束也能极大地加速其反应速率。该反应的加速因子可达百万倍。由于产物对氧化剂不敏感，即使在氧化条件下，此反应也可用于测定含巯基的化合物，如半胱氨酸、谷胱甘肽或蛋白质。检测限低至5×10⁻⁸ M，比经典的5,5'-二硫代双-(2-硝基苯甲酸)法的检测限低十倍。此外，该反应可在pH值为6.5至7.5之间进行，从而降低硫醇的自发氧化速率。此外，我们还证明了4-硝基-α-烷基-1,8-萘二甲酰亚胺可用于显示肽、蛋白质和活细胞中的巯基。
