Irreversible inactivation of the flavoenzyme alcohol oxidase with acetylenic alcohols

Alcohol oxidase is irreversibly inactivated by the acetylenic substrates propargyl alcohol and 1,4-butynediol. In both cases, inactivation results from affinity labeling of amino acid residues in the active site of the enzyme by propynal and 4-hydroxy-2-butynal, the electrophilic products of the oxidation of these alcohols. The inactivation by 4-hydroxy-2-butynal occurs with the aldehyde bound in the active site of the enzyme in the orientation which is opposite to that in which it had been produced. Alcohol oxidase is inactivated by acetylenic substrates in a fundamentally different manner than are the formally similar flavin-dependent α-hydroxy acid oxidases.