Synthesis, Structure, and Reactivity of Model Complexes of Copper Nitrite Reductase

Casella, Luigi; Carugo, Oliviero; Gullotti, Michele; Doldi, Sergio; Frassoni, Massimiliano

doi:10.1021/ic950392o

Cited by 93 publications

(105 citation statements)

References 59 publications

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“…Additionally, the nearly linear N ax -Cu-N axЈ angle in tbp, 176.2°, bends a bit off-axis in Tsh, 167.5°, whereas the N eq -Cu-N ax and N eq -Cu-N axЈ angles increase by 5.6 and 3.1°, respectively. The five-coordinated form is almost identical to the Cu(II) structure reported by Casella et al (57) (CSD code ZUBHOT), whereas the three-coordinated counterpart most closely mimics the Tsh copper(I) structure reported by Sorrell et al (58) (CSD code PIVNOX). A CSD search for five-coordinated, dihydrate copper structures also coordinated by three nitrogen atoms, returned seven structures-all Cu(II)-with several tbp examples similar to the hydrated version of EfaCBM33A seen in 4ALC (Table 4).…”

Section: Lpmo Copper Oxidation State Determination By Analogy To Smalsupporting

confidence: 75%

Structural and Electronic Snapshots during the Transition from a Cu(II) to Cu(I) Metal Center of a Lytic Polysaccharide Monooxygenase by X-ray Photoreduction

Gudmundsson¹,

Kim²,

Wu³

et al. 2014

Journal of Biological Chemistry

107

105

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Background: Lytic polysaccharide monooxygenases (LPMOs) exhibit a copper center that binds dioxygen for catalysis. Results: We present LPMO structures from Cu(II) to Cu(I) and analyze the transition with quantum mechanical calculations. Conclusion: Reduction changes the copper coordination state but requires only minor structural and electronic changes. Significance: These structures provide insight into LPMO catalytic activation for further mechanistic studies.

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Section: Lpmo Copper Oxidation State Determination By Analogy To Smalsupporting

confidence: 75%

Structural and Electronic Snapshots during the Transition from a Cu(II) to Cu(I) Metal Center of a Lytic Polysaccharide Monooxygenase by X-ray Photoreduction

Gudmundsson¹,

Kim²,

Wu³

et al. 2014

Journal of Biological Chemistry

107

105

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“…[10,11] The sizeable intensity of the azido-Cu II LMCT band indicates that it is electric dipole allowed; this implies that there must be good overlap between the donor, π(N 3 -), and acceptor, d x 2 -y 2, orbitals, [11] and therefore that azide binds in the Cu equatorial plane. In addition, as observed systematically for copper(II)-azido complexes, [9,[10][11][12] azide binding is accompanied by an increase in the absorption of the LF bands. For the azido adducts of [Cu 2 PHI] 4+ the interpretation of the CD spectra is relatively simple.…”

Section: Characterization Of the Azido Adducts Of Copper-phi Complexessupporting

confidence: 57%

Ligand Binding, Conformational and Spectroscopic Properties, and Biomimetic Monooxygenase Activity by the Trinuclear Copper–PHI Complex Derived from L‐Histidine

et al. 2008

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The trinuclear copper(II) complex derived from the octadentate N‐donor ligand PHI [piperazine‐1,4‐bis(4‐{N‐[1‐acetoxy‐3‐(1‐methyl‐1H‐imidazol‐4‐yl)]‐2‐propyl}‐N‐(1‐methyl‐1H‐imidazol‐2‐ylmethyl)aminobutyl)] contains two equivalent CuA centers bound by tridentate arms and a CuB center bound by a central didentate residue. The conformational and ligand binding properties of the complex were extensively studied by various spectroscopic techniques (UV/Vis, CD, NMR, EPR) to probe its behavior in solution. Studies on the binding properties of the complex performed with the azide anion as a probe showed that the ligand preferably binds to the CuA centers of the complex and only weakly to the CuB center. The EPR spectra showed the existence of a strong coupling between one of the two CuA centers and the CuB center, which appears to be mediated by a hydroxido‐bridging ligand. Further information about metal binding was obtained by analyzing the NMR spectra of the trinuclear ZnII3–PHI complex, which serves as an analogue of the extremely oxygen sensitive CuI3–PHI complex. The latter complex does not form a stable dioxygen adduct at low temperature, but exhibits an interesting monooxygenase activity. This was studied at low temperature using p‐chlorophenolate as a substrate; the formation of 4‐chlorocatechol in sizeable yield indicates that some of the very reactive CunO2 intermediate should be involved.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

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“…High-resolution nitrite complex (NC) structures revealed an O-coordination of NO 2 − showing a near face-on binding mode (22,23), whereas Cu(II)-NO 2 − model complexes show a vertical binding mode (7,(26)(27)(28)(29). The near face-on coordination manner is thought to facilitate its conversion to side-on NO, which was observed in the crystal structures of CuNiR exposed to NO (22,23,25).…”

Section: Significancementioning

confidence: 91%

Redox-coupled proton transfer mechanism in nitrite reductase revealed by femtosecond crystallography

Fukuda

Tse

Nakane

et al. 2016

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

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Proton-coupled electron transfer (PCET), a ubiquitous phenomenon in biological systems, plays an essential role in copper nitrite reductase (CuNiR), the key metalloenzyme in microbial denitrification of the global nitrogen cycle. Analyses of the nitrite reduction mechanism in CuNiR with conventional synchrotron radiation crystallography (SRX) have been faced with difficulties, because X-ray photoreduction changes the native structures of metal centers and the enzyme–substrate complex. Using serial femtosecond crystallography (SFX), we determined the intact structures of CuNiR in the resting state and the nitrite complex (NC) state at 2.03- and 1.60-Å resolution, respectively. Furthermore, the SRX NC structure representing a transient state in the catalytic cycle was determined at 1.30-Å resolution. Comparison between SRX and SFX structures revealed that photoreduction changes the coordination manner of the substrate and that catalytically important His255 can switch hydrogen bond partners between the backbone carbonyl oxygen of nearby Glu279 and the side-chain hydroxyl group of Thr280. These findings, which SRX has failed to uncover, propose a redox-coupled proton switch for PCET. This concept can explain how proton transfer to the substrate is involved in intramolecular electron transfer and why substrate binding accelerates PCET. Our study demonstrates the potential of SFX as a powerful tool to study redox processes in metalloenzymes.

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Synthesis, Structure, and Reactivity of Model Complexes of Copper Nitrite Reductase

Cited by 93 publications

References 59 publications

Structural and Electronic Snapshots during the Transition from a Cu(II) to Cu(I) Metal Center of a Lytic Polysaccharide Monooxygenase by X-ray Photoreduction

Structural and Electronic Snapshots during the Transition from a Cu(II) to Cu(I) Metal Center of a Lytic Polysaccharide Monooxygenase by X-ray Photoreduction

Ligand Binding, Conformational and Spectroscopic Properties, and Biomimetic Monooxygenase Activity by the Trinuclear Copper–PHI Complex Derived from L‐Histidine

Redox-coupled proton transfer mechanism in nitrite reductase revealed by femtosecond crystallography

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