Electrophilic additions of nitrated fatty acids with biological thiols: comparison with type-2 alkenes

We investigated the adduct formations of cysteine and glutathione with electrophilic substrates. Density functional theory with a continuum model was applied to explore the reactions that serve as models for cell signaling proteins and electrophiles. Biological electrophilic species including nitrated fatty acids (NO ₂ -FAs), 15-deoxy-delta12,14-prostaglandin J2 (15d-PGJ2) and neurotoxic type-2 alkenes were included in our investigation. The reaction sequence begins with a thiol proton transfer with the base, followed by nucleophilic attack, and ends with a second proton transfer to accomplish thiol additions to the substrates. It was observed that adduct formations between the thiols and type-2 alkenes are comparatively more exergonic than those with NO ₂ -FAs and 15d-PGJ2. The type-2 alkenes that were most exergonic in adduct formations were experimentally identified to be the most toxic. The computational approach presented in this work may serve as a convenient method to predict the degree of neurotoxicity.