Mass Spectrometric and Functional Aspects of Drug–Protein Conjugation

Abstract

The covalent binding of drugs (metabolites) to proteins to form drug-protein adducts can have an adverse effect on the body. These adducts are thought to be responsible for idiosyncratic drug reactions including severe drug hypersensitivity reactions. Major advances in proteomics technology have allowed for the identification and quantification of target proteins for certain drugs. Human serum albumin (HSA) and Hb have been identified as accessible targets and potential biomarkers for drug-protein adducts formation, for numerous drugs (metabolites) including β-lactam antibiotics, reactive drug metabolites such as quinone imines (acetaminophen) and acyl glucuronides (diclofenac), and covalent inhibitors (neratinib). For example, MS/MS analysis of plasma samples from patients taking flucloxacillin revealed that flucloxacillin and its 5-hydroxymethyl metabolite formed covalent adducts with lysine residues on albumin via opening of the β-lactam ring. Other proteins such as P450 and keratin are also potential targets for covalent binding. However, for most drugs, the properties of these target proteins including their location, their quantity, the timing of conjugate generation, and their biological function are not well understood. In this review, currently available proteomic technologies including MS/MS analysis to identify antigens, precise location of modifications, and the immunological consequence of hapten-protein complex are illustrated. Moving forward, identification of the nature of the antigenic determinants that trigger immune responses to drug-protein adducts will increase our ability to predict idiosyncratic toxicity for a given compound.

Identification and characterization of a naïve CD8+ T cell repertoire for benzylpenicillin

“…This study focused on BP as a drug model since it has been associated with heterogeneous clinical allergic reactions, and it is known to bind covalently to selective lysine residues on proteins . According to the hapten hypothesis, adducts formed inside and outside of the antigen‐presenting cells usually undergo protein processing to generate MHC‐binding peptides that are assumed to contain the drug modification .…”

“…Beta‐lactams are the antibiotics most frequently causing allergic reactions due to their massive use and their ability to form conjugates with proteins . Protein haptenation by covalent conjugation of drugs such as benzylpenicillin (BP) is considered to be one of the key process for immunization and allergic reaction . Significant progress has been made in understanding the immunopathogenesis of allergic drug reactions, and drug‐specific memory T cells have been detected in drug allergic patients .…”

Amoxicillin Inactivation by Thiol-Catalyzed Cyclization Reduces Protein Haptenation and Antibacterial Potency

“…It is generally accepted that the low molecular weight of antibiotics and other drugs prevents them from being recognized by the immune system on their own, for which they require association with larger structures (Landsteiner and Jacobs, 1935). Importantly, numerous drugs or their metabolites are able to bind covalently to proteins, a process known as haptenation (Ariza et al, 2011;Tailor et al, 2016), which renders structures with the potential of being recognized by the immune system and induce an allergic response (Ariza et al, 2015) (Figure 1).…”

Biomonitoring Human Albumin Adducts: The Past, the Present, and the Future

“…Some of the pathways of metabolism can give rise to electrophilic, short-lived intermediates, which can covalently bind to various proteins (Figure 15–17). 82,144,271,272 …”