The crystal structure of poplar apoplastocyanin at 1.8-A resolution. The geometry of the copper-binding site is created by the polypeptide.

Garrett, T.P.J.; Clingeleffer, D J; Guss, J.M.; Rogers, Samuel J.; Freeman, H.C.

doi:10.1016/s0021-9258(17)43220-0

Cited by 128 publications

(35 citation statements)

References 9 publications

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“…Capture of the metal would then, in part, involve a ring flipping of His167 in a trapdoor-like fashion. Such histidine imidazole ring-flipping has been observed in plastocyanin upon removal of copper [22].…”

Section: Metal Binding and Signal Transductionmentioning

confidence: 76%

The crystal structure of pneumococcal surface antigen PsaA reveals a metal-binding site and a novel structure for a putative ABC-type binding protein

Lawrence¹,

Pilling²,

Epa³

et al. 1998

Structure

209

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. The structural topology of PsaA is fundamentally different from that of other ABC-type binding proteins determined thus far in that PsaA lacks the characteristic 'hinge peptides' involved in conformational change upon solute uptake and release. In our structure, the metal-binding site is probably occupied by Zn2+. The site seems to be well conserved amongst related receptors from both Gram-positive and Gram-negative bacteria.

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Section: Metal Binding and Signal Transductionmentioning

confidence: 76%

The crystal structure of pneumococcal surface antigen PsaA reveals a metal-binding site and a novel structure for a putative ABC-type binding protein

Lawrence¹,

Pilling²,

Epa³

et al. 1998

Structure

209

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“…The irregular geometry of the blue copper site appears to be imposed by the protein and the framework in which the ligands are located. Thus, the ligand positions in plastocyanin are essentially unaffected by replacement of Cu(II) with Hg(II) or by removal of Cu(II) to form the apoprotein (Church et al, 1986;Garrett et al, 1984). In plastocyanin, pseudoazurin, and azurin, a high degree of ordering is also Bond lengths (esd = 0.04 A) and dihedral angles for P. nigra var.…”

Section: Resultsmentioning

confidence: 99%

Resonance Raman spectra of plastocyanin and pseudoazurin: evidence for conserved cysteine ligand conformations in cupredoxins (blue copper proteins)

Han

Adman²,

Beppu³

et al. 1991

Biochemistry

108

139

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New resonance Raman (RR) spectra at 15 K are reported for poplar (Populus nigra) and oleander (Oleander nerium) plastocyanins and for Alcaligenes faecalis pseudoazurin. The spectra are compared with those of other blue copper proteins (cupredoxins). In all cases, nine or more vibrational modes between 330 and 460 cm-1 can be assigned to a coupling of the Cu-S(Cys) stretch with Cys ligand deformations. The fact that these vibrations occur at a relatively constant set of frequencies is testimony to the highly conserved ground-state structure of the Cu-Cys moiety. Shifts of the vibrational modes by 1-3 cm-1 upon deuterium exchange can be correlated with N-H...S hydrogen bonds from the protein backbone to the sulfur of the Cys ligand. There is marked variability in the intensities of these Cys-related vibrations, such that each class of cupredoxin has its own pattern of RR intensities. For example, plastocyanins from poplar, oleander, French bean, and spinach have their most intense feature at approximately 425 cm-1; azurins show greatest intensity at approximately 410 cm-1, stellacyanin and ascorbate oxidase at approximately 385 cm-1, and nitrite reductase at approximately 360 cm-1. These variable intensity patterns are related to differences in the electronic excited-state structures. We propose that they have a basis in the protein environment of the copper-cysteinate chromophore. A further insight into the vibrational spectra is provided by the structures of the six cupredoxins for which crystallographic refinements at high resolution are available (plastocyanins from P. nigra, O. nerium, and Enteromorpha prolifera, pseudoazurin from A. faecalis, azurin from Alcaligenes denitrificans, and cucumber basic blue protein). The average of the Cu-S(Cys) bond lengths is 2.12 +/- 0.05 A. Since the observed range of bond lengths falls within the precision of the determinations, this variation is considered insignificant. The Cys ligand dihedral angles are also highly conserved. Cu-S gamma-C beta-C alpha is always near -170 degrees and S gamma-C beta-C alpha-N near 170 degrees. As a result, the Cu-S gamma bond is coplanar with the Cys side-chain atoms and part of the polypeptide backbone. The coplanarity accounts for the extensive coupling of Cu-S stretching and Cys deformation modes as seen in the RR spectrum. The conservation of this copper-cysteinate conformation in cupredoxins may indicate a favored pathway for electron transfer.

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“…This results in unique spectral (λ max ∼ 600 nm; ε ∼ 5000 M –1 cm –1 ) and magnetic (small A || hyperfine coupling) properties of Cu 2+ bound at this protein site, which has a higher reduction potential (∼180–370 mV vs NHE) than aqueous copper (150 mV vs NHE). Rapid electron transfer by this metalloprotein site is due, in large part, to the small inner-sphere reorganization for the similar Cu 2+ and Cu + coordinations. , Of particular relevance here, a very similar structure of the active site residues is maintained in the metal-free apo-protein, − resulting in little conformational change upon either Cu 2+ or Cu + binding (Figure ).…”

Section: Introductionmentioning

confidence: 88%

Shift from Entropic Cu²⁺ Binding to Enthalpic Cu⁺ Binding Determines the Reduction Thermodynamics of Blue Copper Proteins

North

Wilcox

2019

J. Am. Chem. Soc.

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The enthalpic and entropic components of Cu2+ and Cu+ binding to the blue copper protein azurin have been quantified with isothermal titration calorimetry (ITC) measurements and analysis, providing the first such experimental values for Cu+ binding to a protein. The high affinity of azurin for Cu2+ is entirely due to a very favorable binding entropy, while its even higher affinity for Cu+ is due to a favorable binding enthalpy and entropy. The binding thermodynamics provide insight into bond enthalpies at the blue copper site and entropic contributions from desolvation and proton displacement. These values were used in thermodynamic cycles to determine the enthalpic and entropic contributions to the free energy of reduction and thus the reduction potential. The reduction thermodynamics obtained with this method are in good agreement with previous results from temperature-dependent electrochemical measurements. The calorimetry method, however, provides new insight into contributions from the initial (oxidized) and final (reduced) states of the reduction. Since ITC measurements quantify the protons that are displaced upon metal binding, the proton transfer that is coupled with electron transfer is also determined with this method. Preliminary results for Cu2+ and Cu+ binding to the Phe114Pro variant of azurin demonstrate the insight about protein tuning of the reduction potential that is provided by the binding thermodynamics of each metal oxidation state.

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The crystal structure of poplar apoplastocyanin at 1.8-A resolution. The geometry of the copper-binding site is created by the polypeptide.

Cited by 128 publications

References 9 publications

The crystal structure of pneumococcal surface antigen PsaA reveals a metal-binding site and a novel structure for a putative ABC-type binding protein

The crystal structure of pneumococcal surface antigen PsaA reveals a metal-binding site and a novel structure for a putative ABC-type binding protein

Resonance Raman spectra of plastocyanin and pseudoazurin: evidence for conserved cysteine ligand conformations in cupredoxins (blue copper proteins)

Shift from Entropic Cu²⁺ Binding to Enthalpic Cu⁺ Binding Determines the Reduction Thermodynamics of Blue Copper Proteins

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The crystal structure of poplar apoplastocyanin at 1.8-A resolution. The geometry of the copper-binding site is created by the polypeptide.

Cited by 128 publications

References 9 publications

The crystal structure of pneumococcal surface antigen PsaA reveals a metal-binding site and a novel structure for a putative ABC-type binding protein

The crystal structure of pneumococcal surface antigen PsaA reveals a metal-binding site and a novel structure for a putative ABC-type binding protein

Resonance Raman spectra of plastocyanin and pseudoazurin: evidence for conserved cysteine ligand conformations in cupredoxins (blue copper proteins)

Shift from Entropic Cu2+ Binding to Enthalpic Cu+ Binding Determines the Reduction Thermodynamics of Blue Copper Proteins

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Shift from Entropic Cu²⁺ Binding to Enthalpic Cu⁺ Binding Determines the Reduction Thermodynamics of Blue Copper Proteins