Porphyrin to quinone electron transfer across a depsipeptide which forms an α-helical turn

David A. Williamson; Bruce E. Bowler

doi:10.1016/S0020-1693(99)00341-2

Porphyrin to quinone electron transfer across a depsipeptide which forms an α-helical turn

David A. Williamson, Bruce E. Bowler

Chemistry

University of Denver

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

17 Scopus citations

Abstract

A porphyrin linked to a quinone via a three residue depsipeptide, L-proline-L-lactate-L-lactate has been used to investigate the effect of a protein folding interaction on electron transfer rates through a protein medium. Infrared analysis in the amide A (NH stretch region) demonstrates that the major conformation of the compound is an α-helical turn in CH₂Cl₂. A ROESY NMR experiment corroborates the presence of the α-helical turn through observation of a d(αN) (i,i + 3) through-space contact. Time correlated single photon counting fluorescence lifetime measurements on the porphyrin in the presence and absence of the acceptor quinone indicate that electron transfer is very efficient, k(et) = 5.6 ± 0.3 x 10⁸ s^-1, in this compound. Evaluation of the electronic coupling matrix element, H(ab), gives a value of 3.2 ± 0.8 cm^-1, approximately 100-fold larger than the expected value of ~0.03 cm^-1 for electron transfer along the depsipeptide backbone in the absence of any folding interactions. This result demonstrates that long-range non-covalent protein folding interactions can have profound effects on rates of electron transfer. (C) 2000 Elsevier Science S.A.

Original language	English
Pages (from-to)	47-55
Number of pages	9
Journal	Inorganica Chimica Acta
Volume	297
Issue number	1-2
DOIs	https://doi.org/10.1016/S0020-1693(99)00341-2
State	Published - 2000

Funding

Acknowledgment is made to the Donors of the Petroleum Research Fund, administered by the American Chemical Society for support of this research. We also thank the Howard Hughes Medical Institute (HHMI) for major support to the NMR Center at the University of Colorado Health Sciences Center. We thank Tonny de Beer at the NMR Center for assistance with ROESY experiments. We also thank Mike Machczynski and Jay Winkler at the Beckman Institute’s Laser Resource Center (California Institute of Technology, Pasadena, CA) for their willingness to help with the TCSPC fluorescence lifetime studies. Finally, we thank Julanna Gilbert at the University of Denver for use of FT-IR instrumentation.

Funders	Funder number
American Chemical Society

Keywords

Electron transfer rates
Infrared analysis
Peptide hydrogen bonds
Porphyrin
Quinone
ROESY NMR experiment

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10.1016/S0020-1693(99)00341-2

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title = "Porphyrin to quinone electron transfer across a depsipeptide which forms an α-helical turn",

abstract = "A porphyrin linked to a quinone via a three residue depsipeptide, L-proline-L-lactate-L-lactate has been used to investigate the effect of a protein folding interaction on electron transfer rates through a protein medium. Infrared analysis in the amide A (NH stretch region) demonstrates that the major conformation of the compound is an α-helical turn in CH2Cl2. A ROESY NMR experiment corroborates the presence of the α-helical turn through observation of a d(αN) (i,i + 3) through-space contact. Time correlated single photon counting fluorescence lifetime measurements on the porphyrin in the presence and absence of the acceptor quinone indicate that electron transfer is very efficient, k(et) = 5.6 ± 0.3 x 108 s-1, in this compound. Evaluation of the electronic coupling matrix element, H(ab), gives a value of 3.2 ± 0.8 cm-1, approximately 100-fold larger than the expected value of ~0.03 cm-1 for electron transfer along the depsipeptide backbone in the absence of any folding interactions. This result demonstrates that long-range non-covalent protein folding interactions can have profound effects on rates of electron transfer. (C) 2000 Elsevier Science S.A.",

keywords = "Electron transfer rates, Infrared analysis, Peptide hydrogen bonds, Porphyrin, Quinone, ROESY NMR experiment",

author = "Williamson, {David A.} and Bowler, {Bruce E.}",

note = "Funding Information: Acknowledgment is made to the Donors of the Petroleum Research Fund, administered by the American Chemical Society for support of this research. We also thank the Howard Hughes Medical Institute (HHMI) for major support to the NMR Center at the University of Colorado Health Sciences Center. We thank Tonny de Beer at the NMR Center for assistance with ROESY experiments. We also thank Mike Machczynski and Jay Winkler at the Beckman Institute{\textquoteright}s Laser Resource Center (California Institute of Technology, Pasadena, CA) for their willingness to help with the TCSPC fluorescence lifetime studies. Finally, we thank Julanna Gilbert at the University of Denver for use of FT-IR instrumentation. ",

year = "2000",

doi = "10.1016/S0020-1693(99)00341-2",

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pages = "47--55",

journal = "Inorganica Chimica Acta",

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TY - JOUR

T1 - Porphyrin to quinone electron transfer across a depsipeptide which forms an α-helical turn

AU - Williamson, David A.

AU - Bowler, Bruce E.

N1 - Funding Information: Acknowledgment is made to the Donors of the Petroleum Research Fund, administered by the American Chemical Society for support of this research. We also thank the Howard Hughes Medical Institute (HHMI) for major support to the NMR Center at the University of Colorado Health Sciences Center. We thank Tonny de Beer at the NMR Center for assistance with ROESY experiments. We also thank Mike Machczynski and Jay Winkler at the Beckman Institute’s Laser Resource Center (California Institute of Technology, Pasadena, CA) for their willingness to help with the TCSPC fluorescence lifetime studies. Finally, we thank Julanna Gilbert at the University of Denver for use of FT-IR instrumentation.

PY - 2000

Y1 - 2000

N2 - A porphyrin linked to a quinone via a three residue depsipeptide, L-proline-L-lactate-L-lactate has been used to investigate the effect of a protein folding interaction on electron transfer rates through a protein medium. Infrared analysis in the amide A (NH stretch region) demonstrates that the major conformation of the compound is an α-helical turn in CH2Cl2. A ROESY NMR experiment corroborates the presence of the α-helical turn through observation of a d(αN) (i,i + 3) through-space contact. Time correlated single photon counting fluorescence lifetime measurements on the porphyrin in the presence and absence of the acceptor quinone indicate that electron transfer is very efficient, k(et) = 5.6 ± 0.3 x 108 s-1, in this compound. Evaluation of the electronic coupling matrix element, H(ab), gives a value of 3.2 ± 0.8 cm-1, approximately 100-fold larger than the expected value of ~0.03 cm-1 for electron transfer along the depsipeptide backbone in the absence of any folding interactions. This result demonstrates that long-range non-covalent protein folding interactions can have profound effects on rates of electron transfer. (C) 2000 Elsevier Science S.A.

AB - A porphyrin linked to a quinone via a three residue depsipeptide, L-proline-L-lactate-L-lactate has been used to investigate the effect of a protein folding interaction on electron transfer rates through a protein medium. Infrared analysis in the amide A (NH stretch region) demonstrates that the major conformation of the compound is an α-helical turn in CH2Cl2. A ROESY NMR experiment corroborates the presence of the α-helical turn through observation of a d(αN) (i,i + 3) through-space contact. Time correlated single photon counting fluorescence lifetime measurements on the porphyrin in the presence and absence of the acceptor quinone indicate that electron transfer is very efficient, k(et) = 5.6 ± 0.3 x 108 s-1, in this compound. Evaluation of the electronic coupling matrix element, H(ab), gives a value of 3.2 ± 0.8 cm-1, approximately 100-fold larger than the expected value of ~0.03 cm-1 for electron transfer along the depsipeptide backbone in the absence of any folding interactions. This result demonstrates that long-range non-covalent protein folding interactions can have profound effects on rates of electron transfer. (C) 2000 Elsevier Science S.A.

KW - Electron transfer rates

KW - Infrared analysis

KW - Peptide hydrogen bonds

KW - Porphyrin

KW - Quinone

KW - ROESY NMR experiment

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U2 - 10.1016/S0020-1693(99)00341-2

DO - 10.1016/S0020-1693(99)00341-2

M3 - Article

AN - SCOPUS:0033796655

SN - 0020-1693

VL - 297

SP - 47

EP - 55

JO - Inorganica Chimica Acta

JF - Inorganica Chimica Acta

IS - 1-2

ER -

Porphyrin to quinone electron transfer across a depsipeptide which forms an α-helical turn

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