Publications by authors named "Joshua Kyle Stanfield"

Cytochrome P450 enzymes (CYPs) have attracted much promise as biocatalysts in a push for cleaner and more environmentally friendly catalytic systems. However, changing the substrate specificity of CYPs, such as CYP102A1, can be a challenging task, requiring laborious mutagenesis. An alternative approach is the use of decoy molecules that "trick" the enzyme into becoming active by impersonating the native substrate.

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Catching the structure of cytochrome P450 enzymes in flagrante is crucial for the development of P450 biocatalysts, as most structures collected are found trapped in a precatalytic conformation. At the heart of P450 catalysis lies Cpd I, a short-lived, highly reactive intermediate, whose recalcitrant nature has thwarted most attempts at capturing catalytically relevant poses of P450s. We report the crystal structure of P450BM3 mimicking the state in the precise moment preceding epoxidation, which is in perfect agreement with the experimentally observed stereoselectivity.

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Tetraphenylporphyrin (TPP) is a symmetrically substituted synthetic porphyrin whose properties can be readily modified, providing it with significant advantages over naturally occurring porphyrins. Herein, we report the first example of a stable complex between a native biomolecule, the haemoprotein HasA, and TPP as well as its derivatives. The X-ray crystal structures of nine different HasA-TPP complexes were solved at high resolutions.

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We report an OmpF loop deletion mutant, which improves the cellular uptake of external additives into an Escherichia coli whole-cell biocatalyst. Through co-expression of the OmpF mutant with wild-type P450BM3 in the presence of decoy molecules, the yield of the whole-cell biotransformation of benzene could be considerably improved. Notably, with the decoy molecule C7AM-Pip-Phe the yield duodecupled from 5.

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We report the enhanced cis- and enantioselective cyclopropanation of styrene catalysed by cytochrome P450BM3 in the presence of dummy substrates, i.e. decoy molecules.

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Cytochrome P450BM3 has long been regarded as a promising candidate for use as a biocatalyst, owing to its excellent efficiency for the hydroxylation of unactivated C-H bonds. However, because of its high substrate specificity, its possible applications have been severely limited. Consequently, various approaches have been proposed to overcome the enzyme's natural limitations, thereby expanding its substrate scope to encompass non-native substrates, evoking chemoselectivity, regioselectivity and stereoselectivity and enabling previously inaccessible chemical conversions.

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Despite CYP102A1 (P450BM3) representing one of the most extensively researched metalloenzymes, crystallisation of its haem domain upon modification can be a challenge. Crystal structures are indispensable for the efficient structure-based design of P450BM3 as a biocatalyst. The abietane diterpenoid derivative N-abietoyl-l-tryptophan (AbiATrp) is an outstanding crystallisation accelerator for the wild-type P450BM3 haem domain, with visible crystals forming within 2 hours and diffracting to a near-atomic resolution of 1.

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Haem substitution is an effective approach to tweak the function of haemoproteins. Herein, we report a facile haem substitution method for self-sufficient cytochrome P450BM3 (CYP102A1) from Bacillus megaterium utilising the transpeptidase Sortase A from Staphylococcus aureus. We successfully constructed Mn-substituted BM3 and investigated its catalytic activity.

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An Escherichia coli whole-cell biocatalyst for the direct hydroxylation of benzene to phenol has been developed. By adding amino acid derivatives as decoy molecules to the culture medium, wild-type cytochrome P450BM3 (P450BM3) expressed in E.coli can be activated and non-native substrates hydroxylated, without supplementing with NADPH.

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The selective hydroxylation of benzene to phenol, without the formation of side products resulting from overoxidation, is catalyzed by cytochrome P450BM3 with the assistance of amino acid derivatives as decoy molecules. The catalytic turnover rate and the total turnover number reached 259 min  P450BM3 and 40 200 P450BM3 when N-heptyl-l-proline modified with l-phenylalanine (C7-l-Pro-l-Phe) was used as the decoy molecule. This work shows that amino acid derivatives with a totally different structure from fatty acids can be used as decoy molecules for aromatic hydroxylation by wild-type P450BM3.

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