Cellular proteins and small-molecule nucleophiles

Cellular proteins and small-molecule nucleophiles refers to a broad array of intracellular molecules that serve as reactive sites for electrophilic drugs, particularly alkylating agents used in chemotherapy. These drugs form strong covalent bonds with nucleophilic centers, including the sulfhydryl groups of cysteine residues and glutathione, as well as amino and phosphate groups within the cellular proteome [1]. While the therapeutic intent of these agents is often the alkylation of DNA to induce apoptosis in cancer cells, their interaction with proteins and small molecules like glutathione is a major determinant of their pharmacological activity, metabolic clearance, and side-effect profile [2]. For instance, the conjugation of reactive drug metabolites with glutathione is a primary detoxification mechanism, and its depletion can lead to increased oxidative stress and cellular damage [3]. Protein alkylation can further disrupt essential enzymatic functions and signaling pathways, contributing to the drug's cytotoxic effects [4]. Because this target encompasses thousands of different molecular species rather than a single protein, it is used in pharmacological contexts to describe the non-specific chemical reactivity and multi-target nature of certain cytotoxic compounds [1]. This broad reactivity often results in a narrow therapeutic index and significant systemic toxicity, as the drugs do not discriminate between cancerous and healthy cellular constituents [2]. References: [1] DrugBank Online, Mechlorethamine (DB00888); [2] Colvin, O. M. (2003), Holland-Frei Cancer Medicine; [3] PubChem, Mechlorethamine (CID 4033); [4] National Cancer Institute, Alkylating Agent Definition.

Other names

Cellular nucleophilesIntracellular nucleophilesProteome and small-molecule nucleophilesNucleophilic cellular constituents

Drugs targeting this group act via covalent alkylation of nucleophilic functional groups, such as sulfhydryl, amino, hydroxyl, and phosphate groups, leading to the modification of proteins and the depletion of small-molecule nucleophiles like glutathione [1][2].