Plastocyanin

Freeman, H.C.; Guss, J.M.

doi:10.1002/0470028637.met184

Cited by 4 publications

(5 citation statements)

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“…A well-studied protein redox site is the blue copper, or type 1 copper, site found in small proteins (e.g., plastocyanin, azurin) and multicopper oxidases (e.g., laccase, ascorbate oxidase), which have trigonal copper coordination by a Cys thiolate and two His residues, as well as weak axial ligation, in both the oxidized (Cu 2+ ) and reduced (Cu + ) proteins, as shown for azurin (Figure ).…”

Section: Introductionmentioning

confidence: 99%

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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Section: Introductionmentioning

confidence: 99%

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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“…Blue copper proteins such as plastocyanin (Pc) and azurin (Az) function as electron shuttles in energy conversion systems, although the biological role of blue copper protein classified into phytocyanin has not been hitherto understood. Pc is widely distributed in the thylakoid membranes within the chloroplasts of higher plants, green algae and cyanobacteria, and transfers electrons from photosystem II to photosystem I [1]. Az is in the periplasmic space of several Gram‐negative bacteria, such as Alcaligenes , Achromobacter , Pseudomonas , and Methylomonas [2].…”

Section: Introductionmentioning

confidence: 99%

The alkaline transition of blue copper proteins, Cucumis sativus plastocyanin and Pseudomonas aeruginosa azurin

Sakurai¹

2006

FEBS Letters

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Autoreduction of Cucumis sativus plastocyanin and Pseudomonas aeruginosa azurin took place at alkaline pHs, having been accompanied by the decrease in the intensities of the charge transfer band, Cys-S-(π)→Cu(II) at 597 and 626 nm, and the Cu(II)-EPR signals with small AII values of 6.5 x 10-3 and 5.3 x 10-3 cm-1 for plastocyanin and azurin, respectively. Further, an extra Cu(II)-EPR signal with a large AII value of 21 x 10-3 cm-1 also reversibly emerged with increasing pH. Plastocyanin and azurin are in an equilibrium of the three forms at alkaline pHs Dear Professor Richard Cogdell Editor FEBS LettersThank you very much for your suggestion to tidy us some of English before to submit the revised manuscript to FEBS Letters (FEBSLETTERS-S-05-01041R1). English was polished up by the professional English correction service as follows.About twenty "the" and "a' were deleted or added (not indicated).About fifteen commas were added (not indicated).Every "pH's" was converted to "pHs".Single form was changed to plural form and vice versa for some points.Other alterations are as follows. P2. Line 3: "has not been known" was change to "has not been hitherto understood". P2. Line 16: "solved" was deleted.P2. Line 17: "that" which had been deleted in the original manuscript was added.P2. Line 23 and others: "high alkaline pH's" was changed to "highly alkaline pHs". P3. Line 3: "till" was changed to "until".P3. Results and discussion, Lines 7 and 11 The order of words were changed from "slightly shifted" to "shifted slightly" and "in only" to "only in".P3. Line 5 from bottom: "with the spin Hamiltonian parameters" was added after "signal" and "typical to" was changed to "typical of". P4. Line 6: "recovered as that" was changed to "recovered to the level of that". P4. Line 11: "not only Pc was reduced" was changed to "not only was Pc reduced,". P4. Line 17: "the form to give" was changed to "the form giving". P4. Line 18: "In order to ascertain that" was converted to "In order to ascertain whether". P5. Line 21: "As conclusion" was changed to "In conclusion". P5. Line 3 from bottom: "under study" was changed to "being studied as to".Titles of cited papers were checked to be correct. Sincerely yours, Takeshi Sakurai Cover LetterAbout twenty "the" and "a' were deleted or added (not indicated).About fifteen commas were added (not indicated).Every "pH's" was converted to "pHs".Single form was changed to plural form and vice versa for some points.Other alterations are as follows. P2. Line 3: "has not been known" was change to "has not been hitherto understood". P2. Line 16: "solved" was deleted.P2. Line 17: "that" which had been deleted in the original manuscript was added.P2. Line 23 and others: "high alkaline pH's" was changed to "highly alkaline pHs". P3. Line 3: "till" was changed to "until".P3. Results and discussion, Lines 7 and 11 The order of words were changed from "slightly shifted" to "shifted slightly" and "in only" to "only in".P3. Line 5 from bottom: "with the spin Hamiltonian parameters" was added after "s...

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“…In addition to being an important class of electron-transfer (ET) proteins (4)(5)(6)(7)(8)(9)(10)(11)(12), cupredoxins can be enzymes that catalyze biological reactions (13)(14)(15). The ET cupredoxins include blue (or type 1) copper and purple Cu A proteins, whereas enzymatic cupredoxins include the red (or type 2) copper protein.…”

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confidence: 99%

“…The difference in color arises from subtle differences in the geometry and ligand donor set about the copper active site (12). For example, blue copper proteins, such as plastocyanin, azurin, laccase, NIR, and ceruloplasmin, have a mononuclear copper active site, the copper-thiolate bond of which resides in a trigonal geometry about the copper ion in addition to two copper-histidine coordinations (1,8,9,11,26) (Fig. 1A).…”

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confidence: 99%

Experimental evidence for a link among cupredoxins: Red, blue, and purple copper transformations in nitrous oxide reductase

Savelieff¹,

Wilson²,

Youssef³

et al. 2008

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

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The cupredoxin fold is an important motif in numerous proteins that are central to several critical cellular processes ranging from aerobic and anaerobic respiration to catalysis and iron homeostasis. Three types of copper sites have been found to date within cupredoxin folds: blue type 1 (T1) copper, red type 2 (T2) copper, and purple Cu A. Although as much as 90% sequence difference has been observed among some members of this superfamily of proteins that span several kingdoms, sequence alignment and phylogenic trees strongly suggest an evolutionary link and common ancestry. However, experimental evidence for such a link has been lacking. We report herein the observation of pH-dependent transformation between blue T1 copper, red T2 copper, and the native purple Cu A centers of nitrous oxide reductase (N2OR) from Paracoccus denitrificans. The blue and red copper centers form initially before they are transformed into purple Cu A center. This transformation process is pH-dependent, with lower pH resulting in fewer trapped T1 and T2 coppers and faster transition to purple Cu A. These observations suggest that the purple CuA site contains the essential elements of T1 and T2 copper centers and that the Cu A center is preferentially formed at low pH. Therefore, this work provides an underlying link between the various cupredoxin copper sites and possible experimental evidence in vitro for the evolutionary relationship between the cupredoxin proteins. The findings also lend physiological relevance to cupredoxin site biosynthesis.blue type 1 copper ͉ purple copper CuA ͉ red type 2 copper ͉ folding ͉ kinetics

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Plastocyanin

Cited by 4 publications

References 82 publications

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

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

The alkaline transition of blue copper proteins, Cucumis sativus plastocyanin and Pseudomonas aeruginosa azurin

Experimental evidence for a link among cupredoxins: Red, blue, and purple copper transformations in nitrous oxide reductase

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Plastocyanin

Cited by 4 publications

References 82 publications

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

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

The alkaline transition of blue copper proteins, Cucumis sativus plastocyanin and Pseudomonas aeruginosa azurin

Experimental evidence for a link among cupredoxins: Red, blue, and purple copper transformations in nitrous oxide reductase

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

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