scholarly journals Backbone Dynamics of Plastocyanin in Both Oxidation States

2001 ◽  
Vol 276 (50) ◽  
pp. 47217-47226 ◽  
Author(s):  
Ivano Bertini ◽  
Donald A. Bryant ◽  
Stefano Ciurli ◽  
Alexander Dikiy ◽  
Claudio O. Fernández ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Time Scale ◽  
Solution Structure ◽  
Structural Changes ◽  
Dynamic Properties ◽  
Copper Ion ◽  
Backbone Dynamics ◽  
Copper Proteins ◽  
Model Free ◽  
Significant Difference

A model-free analysis based on15NR1,15NR2, and15N-1H nuclear Overhauser effects was performed on reduced (diamagnetic) and oxidized (paramagnetic) forms of plastocyanin fromSynechocystissp. PCC6803. The protein backbone is rigid, displaying a small degree of mobility in the sub-nanosecond time scale. The loops surrounding the copper ion, involved in physiological electron transfer, feature a higher extent of flexibility in the longer time scale in both redox states, as measured from D2O exchange of amide protons and from NH-H2O saturation transfer experiments. In contrast to the situation for other electron transfer proteins, no significant difference in the dynamic properties is found between the two redox forms. A solution structure was also determined for the reduced plastocyanin and compared with the solution structure of the oxidized form in order to assess possible structural changes related to the copper ion redox state. Within the attained resolution, the structure of the reduced plastocyanin is indistinguishable from that of the oxidized form, even though small chemical shift differences are observed. The present characterization provides information on both the structural and dynamic behavior of blue copper proteins in solution that is useful to understand further the role(s) of protein dynamics in electron transfer processes.

scholarly journals 15N magnetic relaxation study of backbone dynamics of the ribosome-associated cold shock response protein Yfia of Escherichia coli.

2007 ◽  
Vol 54 (4) ◽  
pp. 769-775 ◽  
Author(s):  
Igor Zhukov ◽  
Peter Bayer ◽  
Beate Schölermann ◽  
Andrzej Ejchart
Keyword(s):  
Escherichia Coli ◽  
Time Scale ◽  
Magnetic Relaxation ◽  
Solution Structure ◽  
Cold Shock ◽  
Backbone Dynamics ◽  
Terminal Part ◽  
Model Free ◽  
Cold Shock Response ◽  
Shock Response

In the solution structure of the ribosome-associated cold shock response protein Yfia of Escherichia coli in the free state two structural segments can be distinguished: a well structured, rigid N-terminal part displaying a betaalphabetabetabetaalpha topology and a flexible C-terminal tail comprising last 20 amino-acid residues. The backbone dynamics of Yfia protein was studied by (15)N nuclear magnetic relaxation at three magnetic fields and analyzed using model-free approach. The overall diffusional tumbling of the N-terminal part is strongly anisotropic with a number of short stretches showing increased mobility either on a subnanosecond time scale, or a micro- to millisecond time scale, or both. In contrast, the unstructured polypeptide chain of the C-terminal part, which cannot be regarded as a rigid structure, shows the predominance of fast local motions over slower ones, both becoming faster closer to the C-terminus.

scholarly journals Exploring Platelet Chemokine Antimicrobial Activity: Nuclear Magnetic Resonance Backbone Dynamics of NAP-2 and TC-1

2011 ◽  
Vol 55 (5) ◽  
pp. 2074-2083 ◽  
Author(s):  
Leonard T. Nguyen ◽  
Paulus H. S. Kwakman ◽  
David I. Chan ◽  
Zhihong Liu ◽  
Leonie de Boer ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Antimicrobial Activity ◽  
Magnetic Resonance ◽  
Antimicrobial Activities ◽  
Backbone Dynamics ◽  
Dynamic Simulations ◽  
Model Free ◽  
Significant Difference ◽  
Carboxy Terminal ◽  
Nuclear Magnetic

ABSTRACTThe platelet chemokines neutrophil-activating peptide-2 (NAP-2) and thrombocidin-1 (TC-1) differ by only two amino acids at their carboxy-terminal ends. Nevertheless, they display a significant difference in their direct antimicrobial activities, with the longer NAP-2 being inactive and TC-1 being active. In an attempt to rationalize this difference in activity, we studied the structure and the dynamics of both proteins by nuclear magnetic resonance (NMR) spectroscopy. Using15N isotope-labeled protein, we confirmed that the two monomeric proteins essentially have the same overall structure in aqueous solution. However, NMR relaxation measurements provided evidence that the negatively charged carboxy-terminal residues of NAP-2 experience a restricted motion, whereas the carboxy-terminal end of TC-1 moves in an unrestricted manner. The same behavior was also seen in molecular dynamic simulations of both proteins. Detailed analysis of the protein motions through model-free analysis, as well as a determination of their overall correlation times, provided evidence for the existence of a monomer-dimer equilibrium in solution, which seemed to be more prevalent for TC-1. This finding was supported by diffusion NMR experiments. Dimerization generates a larger cationic surface area that would increase the antimicrobial activities of these chemokines. Moreover, these data also show that the negatively charged carboxy-terminal end of NAP-2 (which is absent in TC-1) folds back over part of the positively charged helical region of the protein and, in doing so, interferes with the direct antimicrobial activity.

scholarly journals Solution NMR structures of oxidized and reducedEhrlichia chaffeensisthioredoxin: NMR-invisible structure owing to backbone dynamics

2018 ◽  
Vol 74 (1) ◽  
pp. 46-56
Author(s):  
Garry W. Buchko ◽  
Stephen N. Hewitt ◽  
Wesley C. Van Voorhis ◽  
Peter J. Myler
Keyword(s):  
Active Site ◽  
Solution Structure ◽  
Helical Structure ◽  
Backbone Dynamics ◽  
Redox States ◽  
Nmr Structures ◽  
Significant Difference ◽  
Cd Studies ◽  
Α Helix ◽  
Nmr Solution Structures

Thioredoxins are small ubiquitous proteins that participate in a diverse variety of redox reactionsviathe reversible oxidation of two cysteine thiol groups in a structurally conserved active site. Here, the NMR solution structures of a reduced and oxidized thioredoxin fromEhrlichia chaffeensis(Ec-Trx, ECH_0218), the etiological agent responsible for human monocytic ehrlichiosis, are described. The overall topology of the calculated structures is similar in both redox states and is similar to those of other thioredoxins: a five-stranded, mixed β-sheet (β1–β3–β2–β4–β5) surrounded by four α-helices. Unlike other thioredoxins studied by NMR in both redox states, the1H–15N HSQC spectrum of reducedEc-Trx was missing eight additional amide cross peaks relative to the spectrum of oxidizedEc-Trx. These missing amides correspond to residues Cys35–Glu39 in the active-site-containing helix (α2) and Ser72–Ile75 in a loop near the active site, and suggest a change in backbone dynamics on the millisecond-to-microsecond timescale associated with the breakage of an intramolecular Cys32–Cys35 disulfide bond in a thioredoxin. A consequence of the missing amide resonances is the absence of observable or unambiguous NOEs to provide the distance restraints necessary to define the N-terminal end of the α-helix containing the CPGC active site in the reduced state. This region adopts a well defined α-helical structure in other reported reduced thioredoxin structures, is mostly helical in oxidizedEc-Trx and CD studies ofEc-Trx in both redox states suggests there is no significant difference in the secondary structure of the protein. The NMR solution structure of reducedEc-Trx illustrates that the absence of canonical structure in a region of a protein may be owing to unfavorable dynamics prohibiting NOE observations or unambiguous NOE assignments.

The Toxicity Effect of Echium Amoenum on the Liver and Kidney of Mice.

2020 ◽  
Vol 17 ◽  
Author(s):  
Mozhgan Ghorbani ◽  
Atefeh Araghi ◽  
Nabi Shariatifar ◽  
Seyed Hooman Mirbaha ◽  
Behrokh Marzban Abbasabadi ◽  
...  
Keyword(s):  
Pyrrolizidine Alkaloids ◽  
Biochemical Analysis ◽  
Liver Enzymes ◽  
Copper Ion ◽  
Control Group ◽  
Dependent Manner ◽  
Toxicity Effect ◽  
Significant Difference ◽  
Liver And Kidney ◽  
Echium Amoenum

Aims: The aim of this study was to investigate the toxic effect of Echium amoenum plants on the liver and kidney of animal model. Background: Echium amoenum is one of the medicinal plants containing pyrrolizidine alkaloids with several properties which has widely consumed among different communities. Objective: The toxic effects of Echium amoenum on the liver and kidney were investigated in this study. Methods: Sixty mice were kept for 28 days under the appropriate laboratory conditions. Echium amoenum extract (25, 12.5, 50 mg / kg, ip.) was administered for 28 days. At the end of experiment, blood samples were drawn and liver and kidneys were removed for evaluating hepatotoxicity and nephrotoxicity of extract. Additionally, experiments were conducted to assay the enzymatic and oxidative activities. Results: There was no significant difference in the levels of copper ion in the liver and kidneys among all groups. There was a significant difference in the levels of lipid peroxidation in the liver of treated groups versus control group. The significant difference was not observed in the levels of glutathione of the liver of all groups. However, the levels of glutathione of the kidney significantly decreased in the treated groups versus control group. There was no significant difference in the liver enzymes including ALP, SGOT, and SGPT between all groups. This indicates that damage increase with enhancing the time and concentrations of extract. Biochemical analysis showed the creatinine and urea levels did not change in the treated groups versus control group. Conclusion: According to the present findings, it is suggested that Echium amoenum causes hepatotoxicity and nephrotoxicity effects in dose and time dependent manner.

scholarly journals Commonalities between Copper Neurotoxicity and Alzheimer’s Disease

Toxics ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 4
Author(s):  
Roshni Patel ◽  
Michael Aschner
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Structural Changes ◽  
Copper Ion ◽  
Plaque Formation ◽  
Ion Concentration ◽  
Medical Community ◽  
Disease Etiology ◽  
Parent Protein ◽  
Lead Zinc

Alzheimer’s disease, a highly prevalent form of dementia, targets neuron function beginning from the hippocampal region and expanding outwards. Alzheimer’s disease is caused by elevated levels of heavy metals, such as lead, zinc, and copper. Copper is found in many areas of daily life, raising a concern as to how this metal and Alzheimer’s disease are related. Previous studies have not identified the common pathways between excess copper and Alzheimer’s disease etiology. Our review corroborates that both copper and Alzheimer’s disease target the hippocampus, cerebral cortex, cerebellum, and brainstem, affecting motor skills and critical thinking. Additionally, Aβ plaque formation was analyzed beginning from synthesis at the APP parent protein site until Aβ plaque formation was completed. Structural changes were also noted. Further analysis revealed a relationship between amyloid-beta plaques and copper ion concentration. As copper ion levels increased, it bound to the Aβ monomer, expediting the plaque formation process, and furthering neurodegeneration. These conclusions can be utilized in the medical community to further research on the etiology of Alzheimer’s disease and its relationships to copper and other metal-induced neurotoxicity.

scholarly journals Genetic Deletion of Interleukin-15 Is Not Associated with Major Structural Changes Following Experimental Post-Traumatic Knee Osteoarthritis in Rats

2021 ◽  
Vol 11 (15) ◽  
pp. 7118
Author(s):  
Ermina Hadzic ◽  
Garth Blackler ◽  
Holly Dupuis ◽  
Stephen James Renaud ◽  
Christopher Thomas Appleton ◽  
...  
Keyword(s):  
Articular Cartilage ◽  
Subchondral Bone ◽  
Structural Changes ◽  
Cartilage Damage ◽  
Wild Type ◽  
Significant Difference ◽  
Post Traumatic ◽  
Interleukin 15 ◽  
Joint Trauma ◽  
Surgically Induced

Post-traumatic osteoarthritis (PTOA) is a degenerative joint disease, leading to articular cartilage breakdown, osteophyte formation, and synovitis, caused by an initial joint trauma. Pro-inflammatory cytokines increase catabolic activity and may perpetuate inflammation following joint trauma. Interleukin-15 (IL-15), a pro-inflammatory cytokine, is increased in OA patients, although its roles in PTOA pathophysiology are not well characterized. Here, we utilized Il15 deficient rats to examine the role of IL-15 in PTOA pathogenesis in an injury-induced model. OA was surgically induced in Il15 deficient Holtzman Sprague-Dawley rats and control wild-type rats to compare PTOA progression. Semi-quantitative scoring of the articular cartilage, subchondral bone, osteophyte size, and synovium was performed by two blinded observers. There was no significant difference between Il15 deficient rats and wild-type rats following PTOA-induction across articular cartilage damage, subchondral bone damage, and osteophyte scoring. Similarly, synovitis scoring across six parameters found no significant difference between genetic variants. Overall, IL-15 does not appear to play a key role in the development of structural changes in this surgically-induced rat model of PTOA.

Improving peroxymonosulfate activation by copper ion-saturated adsorbent-based single atom catalysts for the degradation of organic contaminants: electron-transfer mechanism and the key role of Cu single atoms

2021 ◽  
Author(s):  
Jingwen Pan ◽  
Baoyu Gao ◽  
Pijun Duan ◽  
Kangying Guo ◽  
Muhammad Akram ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Organic Contaminants ◽  
High Salinity ◽  
Copper Ion ◽  
Single Atom ◽  
Electron Transfer Mechanism ◽  
Persulfate Oxidation ◽  
Single Atoms ◽  
Oxidation Technology

Nonradical pathway-based persulfate oxidation technology is considered to be a promising method for high-salinity organic wastewater treatment.

scholarly journals Solution Structure of Copper Ion-Induced Molecular Aggregates of Tyrosine Melanin

1999 ◽  
Vol 77 (2) ◽  
pp. 1135-1142 ◽  
Author(s):  
J.M. Gallas ◽  
K.C. Littrell ◽  
S. Seifert ◽  
G.W. Zajac ◽  
P. Thiyagarajan
Keyword(s):  
Solution Structure ◽  
Copper Ion ◽  
Molecular Aggregates
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