NMR study of structure and electron transfer mechanism of Pseudomonas aeruginosa azurin.

Groeneveld, C. M.; Canters, Gerard W.

doi:10.1016/s0021-9258(19)57374-4

Cited by 83 publications

(48 citation statements)

References 26 publications

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“…The electron self-exchange rate constant we measured for the LCuOH/[LCuOH] − couple is much larger: k 11 = 3 × 10 4 M –1 s –1 at −88 °C and estimated to be ∼ 9 × 10 6 M –1 s –1 at 25 °C. This latter value is similar to that reported for type 1 Cu proteins (10 5 – 10 6 M –1 s –1 ). ,− Also, the value we measured at −88 °C is 7 orders of magnitude larger than that measured at −90 °C in CH 2 Cl 2 for [Cu II (TMGqu) 2 ] 2+ /[Cu I (TMGqu) 2 ] + self-exchange (10 –3 M –1 s –1 ) (Figure ), which has been touted as a definitive example of a complex held in an entatic state (in a geometry poised between the extremes typical for Cu I and Cu II species and thus expected to undergo fast ET reactions). − Finally, the estimated k 11 value for LCuOH/[LCuOH] − ET at 25 °C (in CH 2 Cl 2 ) is ∼10 or 100 times larger than those for the known Cu III,II couples supported by imine–oxime or tetramide (H –2 Aib 3 ) ligands (in H 2 O), respectively (Figure ). , In separate work, it was shown for the latter system that the Cu III congener is strictly four-coordinate but the Cu II complex is axially coordinated by one or two solvent water molecules .…”

Section: Discussionsupporting

confidence: 89%

“…Consistent with the fast electron self-exchange kinetics, a low λ value of 0.95 eV was determined for the LCuOH/[LCuOH] − couple that is only slightly larger than those reported for type 1 Cu proteins − , and calculated for the Cu/(TMGqu) 2 and Cu/(DMEGqu) 2 complexes. − The inner sphere reorganization energy derived from our measurements for the LCuOH/[LCuOH] − system is very small (0.45 eV), indicating that almost half of the total energetic cost is due to reorganization of the solvent in the outer coordination sphere (λ o = 0.50 eV). By comparison, λ o values of 0.5–0.6 eV have been reported for redox couples of other systems measured in DMF or CH 2 Cl 2 . , The low λ i is consistent with minimal structural change upon electron self-exchange, as indicated by a small difference in the Cu–N and Cu–X bonds (by ∼0.1 Å), but no other significant reorganization of the coordination sphere for LCuX/[LCuX] − pairs (X = OH or Cl). , Interestingly, the λ i we measured is comparable to that measured for electron exchange involving superoxide/peroxide ligands in the [Cu II (ON–O – )(O 2 •– )/(O 2 2– )] 2+/+ complexes (λ i = 0.4 eV) .…”

Section: Discussionsupporting

confidence: 81%

Section: ■ Discussionsupporting

confidence: 74%

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Low Reorganization Energy for Electron Self-Exchange by a Formally Copper(III,II) Redox Couple

et al. 2019

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The rate constant for electron self-exchange (k 11 ) between LCuOH and [LCuOH] − (L = bis-2,6-(2,6-diisopropylphenyl)carboximidopyridine) was determined using the Marcus cross relation. This work involved measurement of the rate of the cross-reaction between [Bu 4 N][LCuOH] and [Fc][BAr 4F ] (Fc + = ferrocenium; BAr 4 F = tetrakis[3,5-bis(trifluoromethyl)phenyl]borate)) by stopped-flow methods at −88 °C in CH 2 Cl 2 and measurement of the equilibrium constant for the redox process by UV−vis titrations under the same conditions. A value of k 11 = 3 × 10 4 M −1 s −1 (−88 °C) led to estimation of a value 9 × 10 6 M −1 s −1 at 25 °C, which is among the highest values known for copper redox couples. Further Marcus analysis enabled determination of a low reorganization energy, λ = 0.95 ± 0.17 eV, attributed to minimal structural variation between the redox partners. In addition, the reaction entropy (ΔS°) associated with the LCuOH/[LCuOH] − self-exchange was determined from the temperature dependence of the redox potentials, and found to be dependent upon ionic strength. Comparisons to other Cu redox systems and potential new applications for the formally Cu III,II system are discussed.

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Section: Discussionsupporting

confidence: 89%

Section: Discussionsupporting

confidence: 81%

Section: ■ Discussionsupporting

confidence: 74%

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Low Reorganization Energy for Electron Self-Exchange by a Formally Copper(III,II) Redox Couple

et al. 2019

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“…The blue copper protein, azurin (Az), functions as an electron carrier in the bacterial energy conversion system (1,2). The intramolecular electron transfer (ET) reactions in Az in solution have been studied extensively over the last decades by a variety of methods (3)(4)(5)(6)(7).…”

Section: Introductionmentioning

confidence: 99%

Marked changes in electron transport through the blue copper protein azurin in the solid state upon deuteration

Amdursky

Pecht

Sheves

2012

Proc. Natl. Acad. Sci. U.S.A.

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Measuring solid-state electron transport (ETp) across proteins allows studying electron transfer (ET) mechanism(s), while minimizing solvation effects on the process. ETp is, however, sensitive to any static (conformational) or dynamic (vibrational) changes in the protein. Our macroscopic measurements allow extending ETp studies to low temperatures, with the concomitant resolution of lower current densities, because of the larger electrode contact areas. Thus, earlier we reported temperature-independent ETp via the copper protein azurin (Az), from 80 K until denaturation, whereas for apo-Az ETp was temperature dependent above 180 K. Deuteration (H/D substitution) may provide mechanistic information on the question of whether the ETp involves H-bonds in the solid state. Here we report results of kinetic deuterium isotope effect (KIE) measurements on ETp through holo-Az as a function of temperature (30-340 K). Strikingly, deuteration changed ETp from temperature independent to temperature dependent above 180 K. This H/D effect is expressed in KIE values between 1.8 (340 K) and 9.1 (≤180 K). These values are remarkable in light of the previously reported inverse KIE on ET in Az in solution. We ascribe the difference between our KIE results and those observed in solution to the dominance of solvent effects in the latter (larger thermal expansion in H 2 O than in D 2 O), whereas in our case the KIE is primarily due to intramolecular changes, mainly in the low-frequency structural modes of the protein caused by H/D exchange. The observed high KIE values are consistent with a transport mechanism that involves through-H-bonds of the β-sheet structure of Az, likely also those in the Cu coordination sphere.protein monolayer | tunneling | current-voltage

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“…Because the activity of these signaling pathways changes rapidly, a rapid, sensitive monitor of dynamic changes in signal transduction is required. Techniques have been well developed to measure electron transfer between biological molecules, such as nuclear magnetic resonance spectroscopy and electrochemical methods 21 – 23 . Optical methods are mostly characterized by high temporal and spatial resolution, non-contact detection, and high-sensitive visualization based on machine vision 11 , 24 – 28 .…”

Section: Introductionmentioning

confidence: 99%

Electron transfer-triggered imaging of EGFR signaling activity

Tan

et al. 2022

Nat Commun

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In vivo electron transfer processes are closely related to the activation of signaling pathways, and, thus, affect various life processes. Indeed, the signaling pathway activation of key molecules may be associated with certain diseases. For example, epidermal growth factor receptor (EGFR) activation is related to the occurrence and development of tumors. Hence, monitoring the activation of EGFR-related signaling pathways can help reveal the progression of tumor development. However, it is challenging for current detection methods to monitor the activation of specific signaling pathways in complex biochemical reactions. Here we designed a highly sensitive and specific nanoprobe that enables in vivo imaging of electronic transfer over a broad range of spatial and temporal scales. By using the ferrocene-DNA polymer “wire”, the electrons transferred in a biochemical reaction can flow to persistent luminescent nanoparticles and change their electron distribution, thereby altering the optical signal of the particles. This electron transfer-triggered imaging probe enables mapping the activation of EGFR-related signaling pathways in a temporally and spatially precise manner. By offering precise visualization of signaling activity, this approach may offer a general platform not only for understanding molecular mechanisms in various biological processes but also for promoting disease therapies and drug evaluation.

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NMR study of structure and electron transfer mechanism of Pseudomonas aeruginosa azurin.

Cited by 83 publications

References 26 publications

Low Reorganization Energy for Electron Self-Exchange by a Formally Copper(III,II) Redox Couple

Low Reorganization Energy for Electron Self-Exchange by a Formally Copper(III,II) Redox Couple

Marked changes in electron transport through the blue copper protein azurin in the solid state upon deuteration

Electron transfer-triggered imaging of EGFR signaling activity

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