Coupling to Lysine-13 Promotes Electron Tunneling through Carboxylate-Terminated Alkanethiol Self-Assembled Monolayers to Cytochrome <i>c</i>

Niki, Katsumi; Hardy, W. Reef; Hill, Michael G.; Li, H.; Sprinkle, James R.; Margoliash, E.; Fujita, Kyoko; Tanimura, Ryutaro; Nakamura, Nobufumi; Ohno, Hiroyuki; Richards, John H.; Gray, Harry B.

doi:10.1021/jp035392l

Cited by 103 publications

(140 citation statements)

References 24 publications

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“…This behavior has been attributed to a number of mechanisms: (i) dynamic modes of the solvent or protein interior that damp motion along the ET reaction coordinate (so-called ''quantum friction'') (42); (ii) electrode-derived electric field effects that influence proton rearrangements (43); and (iii) larger amplitude gating processes that produce transitions between active vs. inactive states (44)(45)(46). In the electrochemical systems, ET rates plateau in the same range that we observe for the ZnCcP:Cc complexes (200-5,000 s Ϫ1 ) (14,42,44,45). The CcP:Cc crystal systems show that leveling behavior is an intrinsic property of interfacial protein ET and not unique to electrodes.…”

Section: Structures and Redox Properties Of Znccp In Complex With Yccsupporting

confidence: 65%

“…The CcP:Cc crystal systems show that leveling behavior is an intrinsic property of interfacial protein ET and not unique to electrodes. At longer distances of separation however, ET reactions between Cc variants and carboxylic acid-terminated self-assembled monolayers do show marked sensitivity to the interactions that mate the protein to the electrode (14). In particular, substitutions of Lys-13 of rat Cc reduce ET rates by 5 orders of magnitude (14).…”

Section: Structures and Redox Properties Of Znccp In Complex With Yccmentioning

confidence: 99%

“…At longer distances of separation however, ET reactions between Cc variants and carboxylic acid-terminated self-assembled monolayers do show marked sensitivity to the interactions that mate the protein to the electrode (14). In particular, substitutions of Lys-13 of rat Cc reduce ET rates by 5 orders of magnitude (14). Furthermore, cross-linked yCc at the CcP primary WT interface shows much higher ET reactivity than yCc cross-linked to the opposing back face of CcP, despite similar presumed cofactor separations (47).…”

Section: Structures and Redox Properties Of Znccp In Complex With Yccmentioning

confidence: 99%

“…Thus, coupling of ZnCcP electronic states with this HOMO may compensate changes in the orientation and separation of Cc. However, studies by Gray and colleagues (3,14) on Ru-modified Cc (3) and Cc coupled to electrodes via self-assembled monolayers (14) indicate that ET from the heme to the Cc surface reflects the detailed structure of bonding pathways and interfacial contacts (3).…”

Section: Structures and Redox Properties Of Znccp In Complex With Yccmentioning

confidence: 99%

“…As such, interprotein ET is sensitive to structure and dynamics at the interface (1,(4)(5)(6)(7)(8)(9)(10)(11). Residue substitution (achieved either by use of protein homologs, site-directed mutants, or computations) has been a popular and powerful approach for probing how interface composition influences interprotein ET (7,(10)(11)(12)(13)(14). Nevertheless, effects of residue variation on interface structure are not often known.…”

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confidence: 99%

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Effects of interface mutations on association modes and electron-transfer rates between proteins

Kang

Crane

2005

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

109

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Although bonding networks determine electron-transfer (ET) rates within proteins, the mechanism by which structure and dynamics influence ET across protein interfaces is not well understood. Measurements of photochemically induced ET and subsequent charge recombination between Zn-porphyrin-substituted cytochrome c peroxidase and cytochrome c in single crystals correlate reactivity with defined structures for different association modes of the redox partners. Structures and ET rates in crystals are consistent with tryptophan oxidation mediating charge recombination reactions. Conservative mutations at the interface can drastically affect how the proteins orient and dispose redox centers. Whereas some configurations are ET inactive, the wild-type complex exhibits the fastest recombination rate. Other association modes generate ET rates that do not correlate with predictions based on cofactor separations or simple bonding pathways. Inhibition of photoinduced ET at <273 K indicates gating by smallamplitude dynamics, even within the crystal. Thus, different associations achieve states of similar reactivity, and within those states conformational fluctuations enable interprotein ET.cytochrome ͉ protein dynamics ͉ protein-protein interaction ͉ electron tunneling M any long-range electron-transfer (ET) reactions in biology occur across transient protein-protein interfaces. Reaction rates depend on factors that control both electron tunneling and conformational dynamics coupled to protein association processes (1-3). As such, interprotein ET is sensitive to structure and dynamics at the interface (1, 4-11). Residue substitution (achieved either by use of protein homologs, site-directed mutants, or computations) has been a popular and powerful approach for probing how interface composition influences interprotein ET (7,(10)(11)(12)(13)(14). Nevertheless, effects of residue variation on interface structure are not often known.The natural redox partners yeast cytochrome c peroxidase (CcP) and yeast cytochrome c (yCc), whose structure as a complex was first determined in 1992 (15) and later as a covalent complex (16), have served as a paradigm for studying interprotein ET reactions (8,17). Hoffman and colleagues (8) have exploited ZnCcP substitution to photoactivate ET reactions and examine the effects of many structural and chemical perturbations on interprotein ET. In this system, the ZnCcP triplet state ( 3 ZnCcP) reduces Fe(III)Cc, and then back ET recombines the charge separation (Fig. 1). Recently, it has been demonstrated that a Trp-191 3 Phe CcP variant has much slower ET back-rates (k eb ) than wild-type (WT) CcP in the 1:1 complex with yCc (18). Thus, electron hopping through Trp-191 may accelerate the recombination reaction (Fig. 1), in analogy to the natural reaction between CcP compound I and Fe(II)Cc (19). Nevertheless, much slower ET back-rates in the complex between CcP and hCc compared with yCc, both in solution (20) and in crystals (21), indicate that ET across the protein-protein interface limits the overa...

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Section: Structures and Redox Properties Of Znccp In Complex With Yccsupporting

confidence: 65%

Section: Structures and Redox Properties Of Znccp In Complex With Yccmentioning

confidence: 99%

Section: Structures and Redox Properties Of Znccp In Complex With Yccmentioning

confidence: 99%

Section: Structures and Redox Properties Of Znccp In Complex With Yccmentioning

confidence: 99%

mentioning

confidence: 99%

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Effects of interface mutations on association modes and electron-transfer rates between proteins

Kang

Crane

2005

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

109

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Electron Transfer

Finklea¹

2007

Encyclopedia of Electrochemistry

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The sections in this article are Self‐assembled Monolayers ( SAMs ) Blocking SAMs , Pinholes, and Defects Electroactive SAMs Theoretical Model for Electron Transfer Measurements of Kinetic Parameters Electronic Coupling versus Distance Electronic Coupling versus Other Factors Reorganization Energies Future Directions

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