Proximal ligand electron donation and reactivity of the cytochrome P450 ferric-peroxo anion

Santhosh Sivaramakrishnan, Hugues Ouellet, Hirotoshi Matsumura, Shenheng Guan, Pierre Moenne-Loccoz, Alma L. Burlingame, Paul R. Ortiz De Montellano

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

CYP125 from Mycobacterium tuberculosis catalyzes sequential oxidation of the cholesterol side-chain terminal methyl group to the alcohol, aldehyde, and finally acid. Here, we demonstrate that CYP125 simultaneously catalyzes the formation of five other products, all of which result from deformylation of the sterol side chain. The aldehyde intermediate is shown to be the precursor of both the conventional acid metabolite and the five deformylation products. The acid arises by protonation of the ferric-peroxo anion species and formation of the ferryl-oxene species, also known as Compound I, followed by hydrogen abstraction and oxygen transfer. The deformylation products arise by addition of the same ferric-peroxo anion to the aldehyde intermediate to give a peroxyhemiacetal that leads to C-C bond cleavage. This bifurcation of the catalytic sequence has allowed us to examine the effect of electron donation by the proximal ligand on the properties of the ferric-peroxo anion. Replacement of the cysteine thiolate iron ligand by a selenocysteine results in UV-vis, EPR, and resonance Raman spectral changes indicative of an increased electron donation from the proximal selenolate ligand to the iron. Analysis of the product distribution in the reaction of the selenocysteine substituted enzyme reveals a gain in the formation of the acid (Compound I pathway) at the expense of deformylation products. These observations are consistent with an increase in the pK a of the ferric-peroxo anion, which favors its protonation and, therefore, Compound I formation.

Original languageEnglish (US)
Pages (from-to)6673-6684
Number of pages12
JournalJournal of the American Chemical Society
Volume134
Issue number15
DOIs
StatePublished - Apr 18 2012

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Cytochrome P-450 Enzyme System
Anions
Negative ions
Aldehydes
Ligands
Electrons
Selenocysteine
Acids
Protonation
Iron
Cholesterol
Sterols
Metabolites
Mycobacterium tuberculosis
Paramagnetic resonance
Hydrogen
Alcohols
Enzymes
Oxygen
Oxidation

ASJC Scopus subject areas

  • Chemistry(all)
  • Catalysis
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Sivaramakrishnan, S., Ouellet, H., Matsumura, H., Guan, S., Moenne-Loccoz, P., Burlingame, A. L., & Ortiz De Montellano, P. R. (2012). Proximal ligand electron donation and reactivity of the cytochrome P450 ferric-peroxo anion. Journal of the American Chemical Society, 134(15), 6673-6684. https://doi.org/10.1021/ja211499q

Proximal ligand electron donation and reactivity of the cytochrome P450 ferric-peroxo anion. / Sivaramakrishnan, Santhosh; Ouellet, Hugues; Matsumura, Hirotoshi; Guan, Shenheng; Moenne-Loccoz, Pierre; Burlingame, Alma L.; Ortiz De Montellano, Paul R.

In: Journal of the American Chemical Society, Vol. 134, No. 15, 18.04.2012, p. 6673-6684.

Research output: Contribution to journalArticle

Sivaramakrishnan, S, Ouellet, H, Matsumura, H, Guan, S, Moenne-Loccoz, P, Burlingame, AL & Ortiz De Montellano, PR 2012, 'Proximal ligand electron donation and reactivity of the cytochrome P450 ferric-peroxo anion', Journal of the American Chemical Society, vol. 134, no. 15, pp. 6673-6684. https://doi.org/10.1021/ja211499q
Sivaramakrishnan, Santhosh ; Ouellet, Hugues ; Matsumura, Hirotoshi ; Guan, Shenheng ; Moenne-Loccoz, Pierre ; Burlingame, Alma L. ; Ortiz De Montellano, Paul R. / Proximal ligand electron donation and reactivity of the cytochrome P450 ferric-peroxo anion. In: Journal of the American Chemical Society. 2012 ; Vol. 134, No. 15. pp. 6673-6684.
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