Water exchange of intermediates in a non-haem iron, α-ketoglutarate dioxygenase, deacetoxy-/deacetylcephalosporin C synthase

Abstract

Incubation of [2-¹³C, 3-²H]penicillin N 1c and [4-²H]exomethylene cephalosporin C 5b with the enzyme deacetoxy-/deacetylcephalosporin C synthase (DAOC/DAC synthase) in ¹⁸O-labelled water gave oxygenated products showing significant incorporation of ¹⁸O; the observed levels of incorporation from ¹⁸O-labelled water are complementary to the previously reported incorporations which were achieved from molecular oxygen, and we believe this to be a first example of H₂¹⁸O incorporation into enzymic products catalysed by a non-haem iron, α-ketoglutarate dependent dioxygenase, and suggest structures for the exchanging intermediates.