The enzyme, characterized from the bacterium Bacillus subtilis, is a promiscuous phosphotransferase that catalyses mono-O-phosphorylation of a broad spectrum of phenolic and polyphenolic substrates, including flavonoid classes such as isoflavones, flavones, flavonols, flavanones, and flavonolignans, as well as structurally varied scaffolds like stilbenoids, curcuminoids, chalcones, anthraquinones, coumestans, and coumarins. The reaction is carried out by a ping-pong mechanism involving transient autophosphorylation of a histidine residue. Polyphenols are usually phosphorylated at different sites, producing a mixture of mono-phosphorylated products.
