2,5-diketocamphane 1,2-monooxygenase (2,5-DKCMO) and
3,6-diketocamphane 1,6-monooxygenase (3,6-DKCMO) isolated from camphor-grown
Pseudomonas putida ATCC 17453, are key enantio complementary ketolactonases
that promote the initial ring cleavage of the two antipodes of this natural
bicyclic terpene. Their initial characterization over sixty years ago
represented a seminal discovery, being the first confirmed examples of
enzyme-catalysed Baeyer-Villiger oxidations. Interestingly, over the last six
decades, the perceived functional nature of these oxygen-dependent biocatalysts
has transmogrified significantly. Extensive studies that commenced in the
mid-1960s consistently reported that the enzymes were monomeric true
flavoproteins dependent on both FMNH2 and nonheme iron as bound cofactors. The
role of the metal ion, in cooperation with the flavin, was considered to be
essential for the activation of molecular oxygen. However, all of those
criteria have been changed absolutely by subsequent studies, resulting in the
enzymes currently being acknowledged to be metal ion-independent homodimeric
flavin-dependent two-component monooxygenases deploying FMNH2 not as a bound
cofactor, but rather as a distinct cosubstrate.
That transition is a paradigm that serves to illustrate the constantly
evolving nature of scientific knowledge.
Author(s) Details
Andrew Willetts
4 Sv Ivan, 21403 Sutivan, Croatia and Curnow Consultancies,
Helston, TR13 9PQ, UK.
Please see the link:- https://doi.org/10.9734/bpi/rpmab/v4/627
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