Mechanism of formation and quantitation of imines, pyrroles, and stable nonpyrrole adducts in 2,5-hexanedione-treated protein.
Mol Pharmacol 1987 Oct; 32(4):542-548
Evidence was presented for an imine intermediate during in-vitro pyrrolylation of bovine-serum-albumin (BSA) by 2,5-hexanedione (110134) (2,5-HD) in aqueous buffer. Quantitative comparisons were also made between total diketone binding and pyrrole adduct formation as a function of both pH and diketone/amine molar ratio. The findings were consistent with the appearance of nonpyrrole reaction products at high diketone/amine molar excess but not at lower, more physiologically relevant, ratios. The sensitivity and effectiveness of the p-dimethylaminobenzaldehyde (DMAB) assay in the detection of pyrrole adducts was confirmed. The possible significance of these in-vitro findings was discussed in relation to the proposed mechanisms of action of the neurotoxic gamma-diketones. Certain generalizations could be drawn from this study. It appeared that at the relatively low levels of lysine conservation likely to be present after 2,5-HD exposure in-vivo, the DMAB assay can accurately assess protein pyrrole adduct concentrations. Evidence was provided that pyrrolylation can result in significant alterations in protein structure, particularly in those species not constrained by multiple disulfide linkages, an effect presumably related to the extreme hydrophobicity of this derivative.
NIOSH-Publication; NIOSH-Grant; Neurotoxic-effects; Ketones; Amines; Neuropathology; Pyrroles; In-vitro-studies;
Biochem and Genetic Toxicology New York State Dept of Health Empire State Plaza Albany, N Y 12201
Neurotoxic Disorders; Neurotoxic-effects;
New York State Dept of Health, New York, New York