Reactivity of Contact Allergenic Haptens to Amino Acid Residues in a Model Carrier Peptide, and Characterization of Formed Peptide-Hapten Adducts¹

Abstract

The type of chemical reaction between hapten and carrier protein in the formation of a complete antigen in vivo giving rise to an allergic contact dermatitis (ACD, type IV allergy) is essentially unknown. About 4,000 low-molecular organic compounds are known to have allergenic properties. α,β-Unsaturated carbonyl structures are frequently present among these compounds. Haptens giving rise to antibody formation and type I allergy have been shown to add predominantly to lysine in the carrier protein. In this paper, the reactivity of activated type IV haptens to a model peptide is reported. Essentially all amino acids with nucleophilic properties were present in the model peptide. Investigation of the relative reactivities of the amino acid residues to activated haptens under biomimetic conditions is performed in order to determine the proportions between the adducts of the different amino acid moieties. In all cases, the electrophilic α,β-unsaturated haptens were found to be added to the cysteine residue and no lysine adduct was recorded. Nuclear magnetic resonance (NMR) spectroscopy was used to exclude steric hindrance of any amino acid residue in the addition reaction. The hapten-modified peptides were isolated and characterized by NMR and mass spectrometry.

Prediction of the reduced glutathione (GSH) reactivity of dental methacrylate monomers using NMR spectra-Relationship between toxicity and GSH reactivity

“…This is because the reactivity of acrylates and methacrylates with sulfhydryl groups such as GSH and cysteine-containing polypeptides is closely related to their toxicity 5,6) . Besides, methacrylates with α, β-unsaturated carbonyl structures have been reported to possess allergenic properties due to their depletion of GSH 8) . In dentistry, the toxicity of triethylene glycol dimethacrylate (TEGDMA) has been shown to be related to its Received Jun 9, 2009: Accepted Jul 24, 2009 GSH 4,9) reactivity with , resulting in almost total depletion of intracellular GSH via Michael addition predominantly 9) .…”

The phytochemical piceatannol induces the loss of CBL and CBL-associated proteins

“…These data suggest a mechanism of action in which piceatannol enters into cells and is subsequently oxidized into an electrophilic O-benzoquinone that readily reacts with nucleophilic atoms from the amino acid side chains of Cbl (38). This would then lead to the cross-linking of Cbl, explaining the smearing observed by Western blotting after piceatannol treatment (refs.…”

“…We hypothesized that in vitro most proteins would be sensitive to piceatannol-induced protein loss, considering that we have been unable to identify a specific region of Cbl that led to its sensitivity to piceatannol (Fig. 1A) and that there are many different amino acids with nucleophilic atoms in their side chains, none of which are unique to Cbl, which could react with O-benzoquinones including cysteine, methionine, histidine, tryptophan, serine, tyrosine, lysine, arginine, and proline (38). Western blotting of in vitro reactions containing c-Cbl, c-Src, Lyn, or PDGFRh confirmed that, similar to c-Cbl, all of these proteins were lost in the presence of piceatannol and ROS (Fig.…”

A critique of the EC’s expert (draft) reports on the status of alternatives for cosmetics testing to meet the 2013 deadline

“…94% agreement with in vivo data on 18 chemicals ECVAM pre-validation on-going Reactivity Assay) (Ahlfors et al, 2003).…”