A mechanistic analysis of the quantitation of α-hydroxy ketones by the bicinchoninic acid assay.

A new class of compounds amenable to quantification by the bicinchoninic acid (BCA) assay was identified, allowing an expansion of compounds quantifiable within the assay's capacity. In this article, we demonstrate that compounds containing the α-hydroxy ketone structure are easily measured under standard BCA assay conditions. A nonchromophore analyte containing the α-hydroxy ketone structure, 1,3-dihydroxypropan-2-one (commonly known as dihydroxyacetone), and various structural derivatives were explored on an equimolar basis in the BCA assay. Combined with earlier studies exploring α-hydroxy ketones within copper oxidation systems, the data support the mechanism of this class of compound's ability to enolize through an enediol intermediate to generate a strong signal in the BCA assay. This new quantification technique also highlights the potential for α-hydroxy ketones to interfere with other analytes quantified by the BCA assay.