Specificity of a catabolic pathway--a lesson learned from indirect assays.

Studies with purified orcinol hydroxylase suggest that, contrary to previous conclusions, the enzymes of the orcinol pathway cannot transform analogous compounds to common metabolites. The substrate analogues of orcinol uncouple electron flow from reduced nicotinamide adenine dinucleotide to oxygen from the hydroxylation reaction catalyzed by orcinol hydroxylase.