Oxidation of low-spin iron(II) porphyrins by molecular oxygen. An outer sphere mechanism

Chu, Margaret; Castro, C. E.; Hathaway, Gary M.

doi:10.1021/bi00596a017

Cited by 29 publications

(14 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Based solely upon its inability to be inhibited by carbon monoxide and cyanide and yet be oxidized by oxygen, a "C" conformation was assigned this protein and an "outer sphere" mechanism for the oxygen oxidation of the heme in b¡ and hemes generally was postulated. We have recently demonstrated this mechanism for the O2 oxidation of hemes, including an active site model for cyt b$, does occur in homogeneous solution (Chu et al, 1978). These findings, along with the observations noted below, can explain the seemingly anomalous behavior of this cytochrome.…”

Section: Discussionsupporting

confidence: 55%

Oxidation of heme proteins by alkyl halides: a probe for axial inner sphere redox capacity in solution and in whole cells

Bartnicki¹,

Belser²,

Castro³

1978

Biochemistry

Self Cite

View full text Add to dashboard Cite

Iron(II) porphyrins in homogeneous solution, in heme proteins, and in intact human erythrocytes and lysed cells are oxidized by certain alkyl halides to the corresponding iron(III) complexes at room temperature. The mechanism established for the oxidation of hemes in homogeneous solution operates at all levels of biological integrity. It is an axial inner sphere process. Deoxyhemoglobin has about the same reactivity within and without cells. The speed of the reaction with the proteins is primarily governed by the steric accessibility to iron. The reactivity of an array of iron(II) proteins accords well with theoretical prediction. In contrast the reactivity of cytochrome b5 does not. An examination of the oxidation and reduction of this protein was additional mechanistically defined reagents (trinitrobenzene and hydroquinone) shows it to be in the G rather than C conformation. The unusual redox characteristics of this protein can be rationalized on this basis.

show abstract

Section: Discussionsupporting

confidence: 55%

Oxidation of heme proteins by alkyl halides: a probe for axial inner sphere redox capacity in solution and in whole cells

Bartnicki¹,

Belser²,

Castro³

1978

Biochemistry

Self Cite

View full text Add to dashboard Cite

show abstract

“…The longer Fe-P bond in 1 compared to that in Fe(TPP)(PMe,Ph), is almost certainly steric in origin; within 1, the hydrogens on carbons 27,28,3 1, and 32 are 2.50, 2.49, 2.71, and 2. 44 A respectively, from the porphyrin, less than the normal packing distance of 2.9 A (30).…”

Section: Synthesis and Characterization Of The Complexesmentioning

confidence: 99%

“…Trace protons (from water) can promote formation of superoxide (stabilized as H02.) from reaction of O2 with hexacoordinate metalloporphyrins via a one-electron outer-shere process (44,45), and H-abstraction by H02. could also be envisaged.…”

Section: Speculation On Mechanismsmentioning

confidence: 99%

Catalytic decarbonylation of aldehydes using iron(II) porphyrin complexes, and the crystal structure of (5,10,15,20-tetraphenylporphinato)bis(tri-n-butylphosphine)iron(II)

Belani¹,

James²,

Dolphin³

et al. 1988

Can. J. Chem.

View full text Add to dashboard Cite

The complex (5,10,15,20-tetraphenylporphinato)bis(tri-n-butylphosphine)iron(II), 1, has been isolated in a triclinic crysgl form, a = 12.499(3), b = 12.528(2), c = 12.039(2) A, u = 116.39(1), P = 109.79(1), y = 98.13(1)", Z = 1, spacegroup P1.The structure was solved by conventional heavy atom methods and was refined by full-matrix least-squares procedures to R = 0.060 and R,, = 0.070 for 3551 reflections with I ? 3 u(l). The molecule, which has crystallographic 1-Ci symmetry, displays a relatively undistorted pseudo-octahedral coordination geometry with Fe-P = 2.346(1) and Fe-N = 1.998(3) and 1.993(3) A.In CH2C1, solution, 1 reacts with CO and aldehydes to generate the carbonyl(phosphine) derivative, and decarbonylation of phenylacetaldehyde to toluene becomes catalytic under an Ar stream. The aldehyde decarbonylations involve radical pathways via carbonyl loss from PhCH2C0. The hydrogen abstraction/initiation reaction probably utilizes trace O2 (and possibly trace (water); speculative mechanisms are discussed. [Traduit par la revue] Introduction Carbonylation reactions provide key steps in a range of homogeneously catalyzed processes of industrial importance (1, 2). Decarbonylation (for example, of aldehydes: RCHO +

show abstract

“…Extensive literature is dedicated to thermal and photosensitized formation of O 2 Ϫ [13, 22Ϫ24]. Superoxide can also be formed by outer sphere electron transfer from transition metal ion with saturated coordination sphere [25] or, exceptionally, by liberation from superoxide-type complexes in aprotic solvents [26]. Photosensitizers producing superoxide are e.g.…”

Section: Resultsmentioning

confidence: 99%

Classification of Dioxygen Reactions: A Unifying View

Wagnerová¹

2001

Zeitschrift Für Physikalische Chemie

View full text Add to dashboard Cite

Dioxygen Activation / Spin Conservation Rule / Photoinitiated Dioxygen Reactions / ClassificationDioxygen reactions in solution were classified into six classes according to two criteria, the way how the spin ban of dioxygen reaction is circumvented and origin of the activation energy Ϫ thermal energy or energy of the light quantum.Sauerstoff-Reaktionen werden in sechs Klassen gemäß zweier Kriterien klassifiziert: nach der Art auf welche das Spin-Verbot umgangen wird und nach dem Ursprung der Aktivierungsenergie Ϫ thermische Energie oder Energie des Lichtquantums.

show abstract

Oxidation of low-spin iron(II) porphyrins by molecular oxygen. An outer sphere mechanism

Cited by 29 publications

References 9 publications

Oxidation of heme proteins by alkyl halides: a probe for axial inner sphere redox capacity in solution and in whole cells

Oxidation of heme proteins by alkyl halides: a probe for axial inner sphere redox capacity in solution and in whole cells

Catalytic decarbonylation of aldehydes using iron(II) porphyrin complexes, and the crystal structure of (5,10,15,20-tetraphenylporphinato)bis(tri-n-butylphosphine)iron(II)

Classification of Dioxygen Reactions: A Unifying View

Contact Info

Product

Resources

About