Harnessing the mechanism of glutathione reductase for synthesis of active site bound metallic nanoparticles and electrical connection to electrodes

Daniel Scott, Michael Toney, Martin Muzikár

Research output: Contribution to journalArticle

40 Citations (Scopus)

Abstract

It is demonstrated herein that the FAD-dependent enzyme glutathione reductase (GR) catalyzes the NADPH-dependent reduction of AuCl4 -, forming gold nanoparticles at the active site that are tightly bound through the catalytic cysteines. The nanoparticles can be removed from the GR active site with thiol reagents such as 2-mercaptoethanol. The deep enzyme active site cavity stabilizes very small metallic clusters and prevents them from aggregating in the absence of capping ligands. The behavior of the GR-nanoparticle complexes in solution, and their electrochemical properties when immobilized on graphite paper electrodes are presented. It is shown that the borohydride ion, a known reducing agent for GR, is catalytically oxidized by larger GR-nanoparticle (≥ 150 gold atoms) complexes generating catalytic currents, whereas NADPH (the natural reducing agent for GR) is not. It is proposed that the surface of the Toray graphite paper electrode employed here interferes with NADPH binding to the GR-nanoparticle complex. The catalytic currents with borohydride begin at the potential of GR-bound FAD, showing that there is essentially zero resistance to electron transfer (i.e., zero overpotential) from GR-bound FAD through the gold nanoparticle to the electrode.

Original languageEnglish (US)
Pages (from-to)865-874
Number of pages10
JournalJournal of the American Chemical Society
Volume130
Issue number3
DOIs
StatePublished - Jan 23 2008

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Metal Nanoparticles
Glutathione Reductase
Catalytic Domain
Electrodes
Nanoparticles
Flavin-Adenine Dinucleotide
NADP
Gold
Borohydrides
Graphite
Reducing Agents
Reducing agents
Enzymes
Glutathione
Oxidoreductases
Sulfhydryl Reagents
Glutathione Disulfide
Mercaptoethanol
Electrochemical properties
Cysteine

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Harnessing the mechanism of glutathione reductase for synthesis of active site bound metallic nanoparticles and electrical connection to electrodes. / Scott, Daniel; Toney, Michael; Muzikár, Martin.

In: Journal of the American Chemical Society, Vol. 130, No. 3, 23.01.2008, p. 865-874.

Research output: Contribution to journalArticle

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N2 - It is demonstrated herein that the FAD-dependent enzyme glutathione reductase (GR) catalyzes the NADPH-dependent reduction of AuCl4 -, forming gold nanoparticles at the active site that are tightly bound through the catalytic cysteines. The nanoparticles can be removed from the GR active site with thiol reagents such as 2-mercaptoethanol. The deep enzyme active site cavity stabilizes very small metallic clusters and prevents them from aggregating in the absence of capping ligands. The behavior of the GR-nanoparticle complexes in solution, and their electrochemical properties when immobilized on graphite paper electrodes are presented. It is shown that the borohydride ion, a known reducing agent for GR, is catalytically oxidized by larger GR-nanoparticle (≥ 150 gold atoms) complexes generating catalytic currents, whereas NADPH (the natural reducing agent for GR) is not. It is proposed that the surface of the Toray graphite paper electrode employed here interferes with NADPH binding to the GR-nanoparticle complex. The catalytic currents with borohydride begin at the potential of GR-bound FAD, showing that there is essentially zero resistance to electron transfer (i.e., zero overpotential) from GR-bound FAD through the gold nanoparticle to the electrode.

AB - It is demonstrated herein that the FAD-dependent enzyme glutathione reductase (GR) catalyzes the NADPH-dependent reduction of AuCl4 -, forming gold nanoparticles at the active site that are tightly bound through the catalytic cysteines. The nanoparticles can be removed from the GR active site with thiol reagents such as 2-mercaptoethanol. The deep enzyme active site cavity stabilizes very small metallic clusters and prevents them from aggregating in the absence of capping ligands. The behavior of the GR-nanoparticle complexes in solution, and their electrochemical properties when immobilized on graphite paper electrodes are presented. It is shown that the borohydride ion, a known reducing agent for GR, is catalytically oxidized by larger GR-nanoparticle (≥ 150 gold atoms) complexes generating catalytic currents, whereas NADPH (the natural reducing agent for GR) is not. It is proposed that the surface of the Toray graphite paper electrode employed here interferes with NADPH binding to the GR-nanoparticle complex. The catalytic currents with borohydride begin at the potential of GR-bound FAD, showing that there is essentially zero resistance to electron transfer (i.e., zero overpotential) from GR-bound FAD through the gold nanoparticle to the electrode.

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