Regio- and stereoselective hydroxylation of 10-undecenoic acid with a light-driven P450 BM3 biocatalyst yielding a valuable synthon for natural product synthesis

Abstract

We report herein the selective hydroxylation of 10-undecenoic acid with a light-activated hybrid P450 BM3 enzyme. Under previously developed photocatalytic reaction conditions, only a monohydroxylated product is detected by gas chromatography. Hydroxylation occurs exclusively at the allylic position as confirmed from a synthesized authentic standard. Investigation into the stereochemistry of the reaction indicates that the R enantiomer is obtained in 85% ee. The (R)-9-hydroxy-10-undecenoic acid obtained enzymatically is a valuable synthon en route to various natural products further expanding the light-activated P450 BM3 biocatalysis and highlighting the advantages over traditional methods.

Photoassisted Oxidation of Sulfides Catalyzed by Artificial Metalloenzymes Using Water as an Oxygen Source

“…Water would thus act as the oxygen source, leading to an Mn III -OH that would be oxidized into an Mn IV -oxo species by the photogenerated highly oxidative [Ru III (bpy)3] 3+ species. For the 1-Mn homogenous catalyst, the final Mn V -oxo oxidizing species would likely arise from the disproportionation of the Mn IV -oxo species into Mn III and Mn V =O (Scheme 1, Path b) as reported for other manganese porphyrin complexes [15,16] whereas it would be formed upon oxidation of the Mn IV -oxo by the photogenerated [Ru III (bpy)3] 3+ in the 1-Mn-Xln10A system (Scheme 1, pathway a) [14] because disproportionation between complexes embedded in Xln10A is unlikely.…”

“…The former pathway relies on the photo-reduction by diethyldithiocarbamate (DTC) of a Ru II -chromophore that is covalently attached to the apo-P450, which then catalyzes the reductive activation of oxygen leading, in the presence of H + , to a high-valent P450Fe V -oxo species that performs the oxidation of fatty acids [12,13]. Conversely, the oxidative pathway relies on the ability to quench the excited state of a [Ru II (bpy)3] 2+ chromophore with an irreversible electron acceptor such as [Co III (NH3)5Cl] 2+ , in order to form the highly oxidative [Ru III (bpy)3] 3+ , which then catalyzes the twoelectron oxidation of an iron-bound water molecule with formation of the high-valent iron-oxo species (Scheme 1, Path a) [14]. Scheme 1.…”

“…Scheme 1. Reaction pathways for the two-electron oxidation of an organic substrate by light-driven activation of a catalyst: Path (a) two-electron oxidation of an iron-bound water molecule into highvalent P-450-iron-oxo species by [Ru III (bpy)3] 3+ , generated by quenching of the excited state of [Ru II (bpy)3] 2+ by an irreversible electron acceptor ([Co III (NH3)5Cl] 2+ ) [14]; Path (b) one-electron oxidation of an Mn III -OH complex into a porphyrin-Mn IV -oxo species by [Ru III (bpy)3] 3+ , followed by the disproportionation of the Mn IV -oxo species into Mn III and Mn V =O [15,16]. The oxidative pathway was also used with biomimetic systems involving manganese porphyrins as catalysts and water as an oxygen source, which were reported originally by Calvin's group [15], and more recently by Fukuzumi et al [16].…”

Ru(II)-diimine functionalized metalloproteins: From electron transfer studies to light-driven biocatalysis

“…This light-driven P450 biocatalyst was also used in the one-step synthesis of a valuable synthon in route to the synthesis of several natural products. [86] The high photocatalytic activity establishes that the photogenerated reductive species is able to inject electrons to the heme active site and sustain photocatalytic activity. In addition, this approach circumvents the use of the natural electron transfer pathway, reductase and NAD(P)H cofactor, (Figure 4) and could therefore be more applicable to other members of the large family of cytochrome P450 enzymes.…”

Insights into an efficient light-driven hybrid P450 BM3 enzyme from crystallographic, spectroscopic and biochemical studies

“…The sL407C- 1 hybrid enzyme, containing the Ru(bpy) 2 PhenA photosensitizer, 1 , (bpy = 2,2′-bipyridine, PhenA = 5-acetamido-1,10-phenanthroline) attached to the non-native single cysteine residue (L407C) in the P450 BM3 heme domain, showed high photocatalytic activity in the selective hydroxylation of various substrates. [8, 9] The high total turnover numbers and initial reaction rates suggested efficient coupling between electron delivery and oxygen activation at the heme center. We have then employed a combination of X-ray crystallography, site-directed mutagenesis, transient absorption measurements and enzymatic assays to gain some insights into the electron transfer pathway and the photocatalytic activity.…”