Electron-transfer chemistry of Ru-linker-(heme)-modified myoglobin: Rapid intraprotein reduction of a photogenerated porphyrin cation radical

Chad E. Immoos; Angel J. Di Bilio; Michael S. Cohen; Wytze Van Der Veer; Harry B. Gray; Patrick J. Farmer

doi:10.1021/ic049741h

Electron-transfer chemistry of Ru-linker-(heme)-modified myoglobin: Rapid intraprotein reduction of a photogenerated porphyrin cation radical

Chad E. Immoos, Angel J. Di Bilio, Michael S. Cohen, Wytze Van Der Veer, Harry B. Gray, Patrick J. Farmer

Research output: Contribution to journal › Article › peer-review

32 Scopus citations

Abstract

We report the synthesis and characterization of RuC7, a complex in which a heme is covalently attached to a [Ru(bpy)₃]²⁺ complex through a -(CH₂)₇- linker. Insertion of RuC7 into horse heart apomyoglobin gives RuC7Mb, a Ru(heme)-protein conjugate in which [Ru(bpy)₃]²⁺ emission is highly quenched. The rate of photoinduced electron transfer (ET) from the resting (Ru²⁺/Fe ³⁺) to the transient (Ru³⁺/Fe²⁺) state of RuC7Mb is > 10⁸ s^-1; the back ET rate (to regenerate Ru²⁺/Fe³⁺) is 1.4 × 10⁷ s^-1. Irreversible oxidative quenching by [Co(NH₃)₅Cl] ²⁺ generates Ru³⁺/ Fe³⁺: the Ru³⁺ complex then oxidizes the porphyrin to a cation radical (P^.+); in a subsequent step, P^.+ oxidizes both Fe³⁺ (to give Fe ^IV=O) and an amino acid residue. The rate of intramolecular reduction of P^.+ is 9.8 × 10³ s^-1; the rate of ferryl formation is 2.9 × 10³ s^-1. Strong EPR signals attributable to tyrosine and tryptophan radicals were recorded after RuC7MbM³⁺ (M = Fe, Mn) was flash-quenched/frozen.

Original language	English (US)
Pages (from-to)	3593-3596
Number of pages	4
Journal	Inorganic Chemistry
Volume	43
Issue number	12
DOIs	https://doi.org/10.1021/ic049741h
State	Published - Jun 14 2004
Externally published	Yes

ASJC Scopus subject areas

Physical and Theoretical Chemistry
Inorganic Chemistry

Access to Document

10.1021/ic049741h

Cite this

@article{d9a36dc01bca4da890324ad64155de54,

title = "Electron-transfer chemistry of Ru-linker-(heme)-modified myoglobin: Rapid intraprotein reduction of a photogenerated porphyrin cation radical",

abstract = "We report the synthesis and characterization of RuC7, a complex in which a heme is covalently attached to a [Ru(bpy)3]2+ complex through a -(CH2)7- linker. Insertion of RuC7 into horse heart apomyoglobin gives RuC7Mb, a Ru(heme)-protein conjugate in which [Ru(bpy)3]2+ emission is highly quenched. The rate of photoinduced electron transfer (ET) from the resting (Ru2+/Fe 3+) to the transient (Ru3+/Fe2+) state of RuC7Mb is > 108 s-1; the back ET rate (to regenerate Ru2+/Fe3+) is 1.4 × 107 s-1. Irreversible oxidative quenching by [Co(NH3)5Cl] 2+ generates Ru3+/ Fe3+: the Ru3+ complex then oxidizes the porphyrin to a cation radical (P.+); in a subsequent step, P.+ oxidizes both Fe3+ (to give Fe IV=O) and an amino acid residue. The rate of intramolecular reduction of P.+ is 9.8 × 103 s-1; the rate of ferryl formation is 2.9 × 103 s-1. Strong EPR signals attributable to tyrosine and tryptophan radicals were recorded after RuC7MbM3+ (M = Fe, Mn) was flash-quenched/frozen.",

author = "Immoos, {Chad E.} and {Di Bilio}, {Angel J.} and Cohen, {Michael S.} and {Van Der Veer}, Wytze and Gray, {Harry B.} and Farmer, {Patrick J.}",

year = "2004",

month = jun,

day = "14",

doi = "10.1021/ic049741h",

language = "English (US)",

volume = "43",

pages = "3593--3596",

journal = "Inorganic Chemistry",

issn = "0020-1669",

publisher = "American Chemical Society",

number = "12",

}

TY - JOUR

T1 - Electron-transfer chemistry of Ru-linker-(heme)-modified myoglobin

T2 - Rapid intraprotein reduction of a photogenerated porphyrin cation radical

AU - Immoos, Chad E.

AU - Di Bilio, Angel J.

AU - Cohen, Michael S.

AU - Van Der Veer, Wytze

AU - Gray, Harry B.

AU - Farmer, Patrick J.

PY - 2004/6/14

Y1 - 2004/6/14

N2 - We report the synthesis and characterization of RuC7, a complex in which a heme is covalently attached to a [Ru(bpy)3]2+ complex through a -(CH2)7- linker. Insertion of RuC7 into horse heart apomyoglobin gives RuC7Mb, a Ru(heme)-protein conjugate in which [Ru(bpy)3]2+ emission is highly quenched. The rate of photoinduced electron transfer (ET) from the resting (Ru2+/Fe 3+) to the transient (Ru3+/Fe2+) state of RuC7Mb is > 108 s-1; the back ET rate (to regenerate Ru2+/Fe3+) is 1.4 × 107 s-1. Irreversible oxidative quenching by [Co(NH3)5Cl] 2+ generates Ru3+/ Fe3+: the Ru3+ complex then oxidizes the porphyrin to a cation radical (P.+); in a subsequent step, P.+ oxidizes both Fe3+ (to give Fe IV=O) and an amino acid residue. The rate of intramolecular reduction of P.+ is 9.8 × 103 s-1; the rate of ferryl formation is 2.9 × 103 s-1. Strong EPR signals attributable to tyrosine and tryptophan radicals were recorded after RuC7MbM3+ (M = Fe, Mn) was flash-quenched/frozen.

AB - We report the synthesis and characterization of RuC7, a complex in which a heme is covalently attached to a [Ru(bpy)3]2+ complex through a -(CH2)7- linker. Insertion of RuC7 into horse heart apomyoglobin gives RuC7Mb, a Ru(heme)-protein conjugate in which [Ru(bpy)3]2+ emission is highly quenched. The rate of photoinduced electron transfer (ET) from the resting (Ru2+/Fe 3+) to the transient (Ru3+/Fe2+) state of RuC7Mb is > 108 s-1; the back ET rate (to regenerate Ru2+/Fe3+) is 1.4 × 107 s-1. Irreversible oxidative quenching by [Co(NH3)5Cl] 2+ generates Ru3+/ Fe3+: the Ru3+ complex then oxidizes the porphyrin to a cation radical (P.+); in a subsequent step, P.+ oxidizes both Fe3+ (to give Fe IV=O) and an amino acid residue. The rate of intramolecular reduction of P.+ is 9.8 × 103 s-1; the rate of ferryl formation is 2.9 × 103 s-1. Strong EPR signals attributable to tyrosine and tryptophan radicals were recorded after RuC7MbM3+ (M = Fe, Mn) was flash-quenched/frozen.

UR - http://www.scopus.com/inward/record.url?scp=2942547311&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=2942547311&partnerID=8YFLogxK

U2 - 10.1021/ic049741h

DO - 10.1021/ic049741h

M3 - Article

C2 - 15180412

AN - SCOPUS:2942547311

SN - 0020-1669

VL - 43

SP - 3593

EP - 3596

JO - Inorganic Chemistry

JF - Inorganic Chemistry

IS - 12

ER -

Electron-transfer chemistry of Ru-linker-(heme)-modified myoglobin: Rapid intraprotein reduction of a photogenerated porphyrin cation radical

Abstract

ASJC Scopus subject areas

Access to Document

Other files and links

Fingerprint

Cite this