Functional consequences of acetaldehyde binding to proteins.

Acetaldehyde reacts with lysyl residues of proteins to form unstable and stable adducts. The effects of adduct formation on the biological activity of certain proteins were investigated. The covalent binding of acetaldehyde to lysine-dependent enzymes selectively inhibited their catalytic activity. Acetaldehyde adduct formation with tubulin also decreased its ability to assemble into microtubules. In addition, certain lysine residues in the alpha-chain of the tubulin dimer had a selective and enhanced reactivity toward acetaldehyde. This selectivity of binding to the alpha-chain occurred for stable adducts but not unstable adducts, and impaired tubulin assembly correlated with stable adduct formation. These studies indicate that acetaldehyde may preferentially bind to certain key lysine amino groups in proteins, and the resultant binding can cause marked alterations in biological function.