An unexpected promiscuous activity of 4-oxalocrotonate tautomerase: the cis-trans isomerisation of nitrostyrene.

Serendipitous switch: While exploring cis-nitrostyrene as a potential electrophile in Michael-type addition reactions catalysed by the enzyme 4-oxalocrotonate tautomerase (4-OT), it was unexpectedly found that 4-OT catalyses the isomerisation of cis-nitrostyrene to trans-nitrostyrene (k(cat) /K(m) = 1.9×10(3)  M(-1)  s(-1) ).