Cytochrome c oxidase: some current biochemical and biophysical problems

1973 ◽  
Vol 6 (4) ◽  
pp. 389-431 ◽  
Author(s):  
Bo G. Malmström
Keyword(s):  
Chemical Structure ◽  
Mitochondrial Respiratory Chain ◽  
Spectroscopic Properties ◽  
Thermodynamic Theory ◽  
Quantum Mechanical ◽  
Spectroscopic Methods ◽  
Paramagnetic Resonance ◽  
Oxidation Reduction ◽  
Electron Paramagnetic ◽  
Haem Proteins

Few fields of biochemistry have seen such widespread applications of physical theories and techniques as that of biological oxidation. There are obvious reasons for this. Oxidation-reduction reactions form the foundations of bioenergetics, an area which can only be understood in terms of thermodynamic theory. Most components of the mitochondrial respiratory chain contain transition metals, and these elements and their chemical environment can often be studied by modern spectroscopic methods, such as electron-paramagnetic resonance (EPR). The relation between spectroscopic properties and chemical structure of metallo-proteins, e.g. haem proteins, represents one of the few branches of present-day biochemistry to which quantum mechanical calculations can profitably be applied (see, for example, Zerner, Gouterman & Kobayashi, 1966).

scholarly journals SPECTROSCOPICALLY AND/OR STRUCTURALLY INTRIGUING PHTHALOCYANINES AND RELATED COMPOUNDS. PART 3. DIMERIC SYSTEMS, TETRAMERS, AND CONCLUSIONS

2019 ◽  
Vol 62 (11) ◽  
pp. 4-37
Author(s):  
Nagao Kobayashi
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Spectroscopic Data ◽  
Magnetic Circular Dichroism ◽  
Spectroscopic Methods ◽  
Paramagnetic Resonance ◽  
The Third ◽  
Electron Paramagnetic ◽  
Related Compounds

This work is the third part of the review, which presents the properties of a large group of phthalocyanines, which were synthesized and spectroscopically and theoretically studied in works performed under the guidance of the author for the period 2007-2017. Examples of the analysis of spectroscopic data in combination with quantum-chemical calculations of different level are given. As spectroscopic methods, we used the methods of electron absorption, natural and magnetic circular dichroism (CD and MCD) fluorescence, phosphorescence, and electron paramagnetic resonance with time resolution. Based on quantum-chemical calculations, the spectra of (4n + 2) p systems, as well as some 4np antiaromatic systems, were theoretically analyzed. Unlike the first and second parts of the review, this part deals with dimeric and tetrameric systems. <span style="opacity: 0;"> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . </span> <span style="opacity: 0;"> . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . </span>

scholarly journals The Structures, Spectroscopic Properties, and Photodynamic Reactions of Three [RuCl(QN)NO]−Complexes (HQN = 8-Hydroxyquinoline and Its Derivatives) as Potential NO-Donating Drugs

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Leilei Xie ◽  
Lifang Liu ◽  
Wenming Wang ◽  
Zhiou Ma ◽  
Liqun Xu ◽  
...  
Keyword(s):  
Density Functional ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Energy Levels ◽  
Spectroscopic Properties ◽  
Resonance Spectroscopy ◽  
Electronic Effects ◽  
Paramagnetic Resonance ◽  
Time Resolved ◽  
Potential Applications ◽  
Electron Paramagnetic

The structures and spectral properties of three ruthenium complexes with 8-hydroxyquinoline (Hhqn) and their derivatives 2-methyl-8-quinolinoline (H2mqn) and 2-chloro-8-quiolinoline (H2cqn) as ligands (QN = hqn, 2mqn, or 2cqn) were calculated with density functional theory (DFT) at the B3LYP level. The UV-Vis and IR spectra of the three [RuCl(QN)NO]−complexes were theoretically assigned via DFT calculations. The calculated spectra reasonably correspond to the experimentally measured spectra. Photoinduced NO release was confirmed through spin trapping of the electron paramagnetic resonance spectroscopy (EPR), and the dynamic process of the NO dissociation upon photoirradiation was monitored using time-resolved infrared (IR) spectroscopy. Moreover, the energy levels and related components of frontier orbitals were further analyzed to understand the electronic effects of the substituent groups at the 2nd position of the ligands on their photochemical reactivity. This study provides the basis for the design of NO donors with potential applications in photodynamic therapy.

scholarly journals Oxidation-reduction potentials of molybdenum, flavin and iron-sulphur centres in milk xanthine oxidase

1976 ◽  
Vol 157 (2) ◽  
pp. 469-478 ◽  
Author(s):  
R Cammack ◽  
M J Barber ◽  
R C Bray
Keyword(s):  
Xanthine Oxidase ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Bovine Milk ◽  
Resonance Spectroscopy ◽  
Paramagnetic Resonance ◽  
Reduction Potentials ◽  
Point Reduction ◽  
Oxidation Reduction ◽  
Mediator System ◽  
Electron Paramagnetic

1. The mid-point reduction potentials of the various groups in xanthine oxidase from bovine milk were determined by potentiometric titration with dithionite in the presence of dye mediators, removing samples for quantification of the reduced species by e.p.r. (electron-paramagnetic-resonance) spectroscopy. The values obtained for the functional enzyme in pyrophosphate buffer, pH8.2, are: Fe/S centre I, −343 +/- 15mV; Fe/S II, −303 +/- 15mV; FAD/FADH-; −351 +/- 20mV; FADH/FADH2, −236 +/-mV; Mo(VI)/Mo(V) (Rapid), −355 +/- 20mV; Mo(V) (Rapid)/Mo(IV), −355 +/- 20mV. 2. Behaviour of the functional enzyme is essentially ideal in Tris but less so in pyrophosphate. In Tris, the potential for Mo(VI)/Mo(V) (Rapid) is lowered relative to that in pyrophosphate, but the potential for Fe/S II is raised. The influence of buffer on the potentials was investigated by partial-reduction experiments with six other buffers. 3. Conversion of the enzyme with cyanide into the non-functional form, which gives the Slow molybdenum signal, or alkylation of FAD, has little effect on the mid-point potentials of the other centres. The potentials associated with the Slow signal are: Mo(VI)/Mo(V) (Slow), −440 +/- 25mV; Mo(V) (Slow)/Mo(IV), −480 +/- 25 mV. This signal exhibits very sluggish equilibration with the mediator system. 4. The deviations from ideal behaviour are discussed in terms of possible binding of buffer ions or anti-co-operative interactions amongst the redox centres.

scholarly journals Hyperbranched Polymers Modified with Dansyl Units and Their Cu(II) Complexes. Bioactivity Studies

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4574
Author(s):  
Paula Bosch ◽  
Desislava Staneva ◽  
Evgenia Vasileva-Tonkova ◽  
Petar Grozdanov ◽  
Ivanka Nikolova ◽  
...  
Keyword(s):  
Chemical Structure ◽  
Copper Complexes ◽  
Copper Ions ◽  
Hyperbranched Polymers ◽  
Branched Polymers ◽  
Paramagnetic Resonance ◽  
Antibacterial Textiles ◽  
Electron Paramagnetic ◽  
Better Than ◽  
Formation Of Complexes

Two new copper complexes of hyperbranched polymers modified with dansyl units were synthesized and characterized by infrared spectroscopy (IR) and electron paramagnetic resonance (EPR) techniques. It was found that copper ions coordinate predominantly with nitrogen or oxygen atoms of the polymer molecule. The place of the formation of complexes and the number of copper ions involved depend on the chemical structure of the polymer. The antimicrobial activity of the new polymers and their Cu(II) complexes was tested against Gram-negative and Gram-positive bacterial and fungal strains. Copper complexes were found to have activity better than that of the corresponding ligands. The deposition of the modified branched polymers onto cotton fabrics prevents the formation of bacterial biofilms, which indicates that the studied polymers can find application in antibacterial textiles.

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