Low-temperature kinetic measurements of microsecond freeze–hyperquench (MHQ) cytochrome oxidase monitored by UV–visible spectroscopy with a newly designed cuvette

2006 ◽  
Vol 34 (1) ◽  
pp. 136-138 ◽  
Author(s):  
F.G.M. Wiertz ◽  
S. de Vries
Keyword(s):  
Low Temperature ◽  
Cytochrome Oxidase ◽  
Cytochrome C Oxidase ◽  
Room Temperature ◽  
Paracoccus Denitrificans ◽  
Visible Spectroscopy ◽  
Kinetic Measurements ◽  
Intermediate States ◽  
Powder Samples ◽  
Uv Visible

A special cuvette was designed to measure optical changes of MHQ (microsecond freeze–hyperquench) powder samples [Wiertz, Richter, Cherepanov, MacMillan, Ludwig and de Vries (2004) FEBS Lett. 575, 127–130] at temperatures below approx. 250 K. Reduced cytochrome c oxidase from Paracoccus denitrificans was reacted with O2 for 100 μs, frozen as a powder and transferred to the cuvette. Subsequently, cytochrome oxidase was allowed to react further following stepwise increments of the temperature from 100 K up to 250 K while recording spectra between 300 and 700 nm. The temperature was raised only when no further changes in the spectra could be detected. The experiment yielded spectra of the A, PM, F and O intermediate states. This demonstrated that the catalytic cycle of cytochrome oxidase at low temperature is similar to that at room temperature and so verifies the suitability of this method for the study of enzymes with high catalytic-centre activity.

Synthesis and Characterization of Gold Nanoparticles Synthesized in Gel and Paper by Electrolysis

2019 ◽  
Vol 824 ◽  
pp. 163-167
Author(s):  
Pema Dechen ◽  
Ekasith Somsook
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Gold Nanoparticles ◽  
Room Temperature ◽  
Synthesis And Characterization ◽  
Visible Spectroscopy ◽  
Gold Leaf ◽  
Uv Visible ◽  
Scanning Electron

In this report, synthesis and characterization of gold nanoparticles (AuNPs) from gold leaf by electrolysis in two different media (gel and paper) in presence of sodium chloride (NaCl), glucose (C6H12O6) and polyvinyl pyrrolidone (PVP) at room temperature were investigated. Graphite was used as two electrodes, NaCl was used as an electrolyte, C6H12O6 was used as reducing agent and PVP was used as stabilizer to control the aggregation of the nanoparticles. UV-Visible spectroscopy (UV-Vis) and scanning electron microscopy (SEM) were used to confirm the characteristics and morphologies of the synthesized AuNPs.

scholarly journals Electrical Conductivity Studies on Co(II), Cu(II),Ni(II) and Cd(II) Complexes of Azines

2008 ◽  
Vol 5 (4) ◽  
pp. 797-801 ◽  
Author(s):  
M. Revanasiddappa ◽  
Syed Khasim ◽  
S. C. Raghavendra ◽  
C. Basavaraja ◽  
T. Suresh ◽  
...  
Keyword(s):  
Room Temperature ◽  
Molar Conductance ◽  
Molar Ratio ◽  
Temperature Conductivity ◽  
Physical Methods ◽  
Alcoholic Medium ◽  
Electrical Conductivities ◽  
Powder Samples ◽  
Higher Temperature ◽  
Uv Visible

1-Phenyl-4-(2'-hydroxyphenyl-1-yl)di-imino azine, {1P-4-(2' HPDA)} 1, 4(2'-hydroxyphenyl-1-yl)di-imino azine, {1, 4-(2' HPDA)} are derived from benzophenone hydrozone with different aldehydes in presence of few drops of concentrated hydrochloric acid in alcoholic medium. Metal(II) complexes have been prepared by salts of CoCl2, CuCl2, NiCl2and CdCl2reacting with azine ligands dissolved in alcohol in the molar ratio of (1:2). The prepared complexes were characterized by using various physical methodsviz. elemental, molar conductance, magnetic susceptibility, IR, NMR, XRD and UV-Visible. Conductivity of the powder samples were measured by two probe method. Measured electrical conductivities of Co(II), Cu(II), Ni(II) and Cd(II) complexes of azines are reported in this paper. It is found that at room temperature these complexes show insulator behavior. At higher temperature conductivity increases linearly, showing semi conducting behavior.

scholarly journals Low-temperature studies on mixed-valence cytochrome oxidase by using magnetic circular dichroism

1976 ◽  
Vol 159 (3) ◽  
pp. 811-813 ◽  
Author(s):  
T Brittain ◽  
J Springall ◽  
C Greenwood ◽  
A J Thomson
Keyword(s):  
Circular Dichroism ◽  
Low Temperature ◽  
Cytochrome Oxidase ◽  
High Spin ◽  
Room Temperature ◽  
Magnetic Circular Dichroism ◽  
Mixed Valence ◽  
Spin States ◽  
High Spin States ◽  
Circular Dichroïsm

The spin states of the haem components of mixed-valence cytochrome oxidase were studied at room temperature and at temperature down to 20K by using magnetic circular dichroism. The room-temperature studies show the presence of a low-spin ferrous haem together with a low-spin ferric haem, which we attribute to heams a3 and a respectively. At temperatures below 100K it appears that the CO of the mixed-valence CO complex may be irreversibly photolysed, and that in this case haems a and a3 assume their high-spin states. Thus in this enzyme haem-haem interactions appear possible at temperatures below 100K.

scholarly journals Mild and Efficient Tunable Brønsted Acidic Ionic Liquid Catalyzed O-Acetylation and O-Trimethylsilylation with Trimethylsilyl Acetate (TMSOAc) and Hexamethyldisilazane (HMDS)

Catalysts ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 825
Author(s):  
Amit Ravindra Pantawane ◽  
Mayur Thul ◽  
Yi-Jyun Lin ◽  
Michelle Lin ◽  
Wesley Lin ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Ionic Liquids ◽  
Room Temperature ◽  
Visible Spectroscopy ◽  
Acidic Ionic Liquid ◽  
Post Process ◽  
Brønsted Acidic Ionic Liquid ◽  
Acidic Ionic Liquids ◽  
Uv Visible ◽  
Work Up

This report discloses a mild and efficient O-acetylation using easily accessible TMSOAc as a novel acetyl reagent and O-trimethylsilylation using HMDS for various alcohols catalyzed by tunable Brønsted acidic ionic liquids (TBAILs). Imidazolium-based TBAILs were prepared by a two-step atom-economic reaction and acidities measured by using UV-visible spectroscopy. Both protections for alcohols were accomplished at room temperature with good to excellent yields, while the products and TBAILs were separated by simple work-up for O-silylation and column chromatography for O-acetylation. Notably, with the simple post-process, TBAILs catalyst in this solvent free method easily recovered and recycled several times without significant degradation.

Preparation of Green Nanosilver by Ascorbic Acid and its Spectral Properties

2013 ◽  
Vol 749 ◽  
pp. 503-506
Author(s):  
Yang He Luo ◽  
Chun Ming Wang ◽  
Wen Qing Yin ◽  
Ai Hui Liang
Keyword(s):  
Ascorbic Acid ◽  
Spectral Properties ◽  
Room Temperature ◽  
Rayleigh Scattering ◽  
Resonance Rayleigh Scattering ◽  
Visible Spectroscopy ◽  
Laser Scattering ◽  
Transmission Electron ◽  
Uv Visible ◽  
Strong Absorption Peak

In the presence of stabilizer of citrate and room temperature, stable green nanosilver sol was prepared by reduction of AgNO3by ascorbic acid. It was characterized by UV-visible spectroscopy, resonance Rayleigh scattering (RRS) spectroscopy, laser scattering and transmission electron microscopy. Results showed that the nanosilver sol exhibited a RRS peak at 496 nm, a strong absorption peak at 414 nm and the particle size is 12 nm.

scholarly journals Analysis and characterisation of anthocyanins in mulberry fruit

2010 ◽  
Vol 28 (No. 2) ◽  
pp. 117-126 ◽  
Author(s):  
C. Qin ◽  
Y. Li ◽  
W. Niu ◽  
Y. Ding ◽  
R. Zhang ◽  
...  
Keyword(s):  
Food Processing ◽  
Room Temperature ◽  
Morus Alba ◽  
Visible Spectroscopy ◽  
Fruit Extract ◽  
Mulberry Fruit ◽  
Medicinal Food ◽  
Uv Visible ◽  
Mulberry Fruits

The fruit of mulberry (<I>Morus alba</I> L., Moraceae) has been used as medicinal food in China for a long history. The pigment from the fruit extract is a kind of natural colourant for food processing and has potential medical and commercial values. This study focuses on the analysis and characterisation of anthocyanins from mulberry pigment. The fresh mulberry fruits were extracted with the solvent of 95% alcohol/0.1% HC l (1:1, ratio) at room temperature for 4 h in the dark. After the isolation using C-18 column, the pigment was identified with UV-Visible Spectroscopy, HPLC-PAD, LC-MS, and <SUP>1</SUP>HNMR. The results showed that the abundant anthocyanins in mulberry pigment are cyanidin 3-<I>O</I>-rutinoside (60%) and cyanidin 3-<I>O</I>-glucoside (38%). The minor anthocyanins (totally 2%) are pelargonidin 3-<I>O</I>-glucoside and pelargonidin 3-<I>O</I>-rutinoside.

scholarly journals Congo Red and Nigrosine Dye Degradation using Dimethyl Dioxirane as an Oxidising Agent

2021 ◽  
Vol 37 (5) ◽  
pp. 1221-1228
Author(s):  
S. Vinotha ◽  
A.Leema Rose
Keyword(s):  
Congo Red ◽  
Room Temperature ◽  
Functional Group ◽  
Dye Degradation ◽  
Visible Spectroscopy ◽  
Before And After ◽  
Ft Ir ◽  
Combined Action ◽  
Uv Visible ◽  
Ft Ir Spectroscopy

The advanced oxidation of Congo red (CR) and Nigrosine (NI) using the combined action of dimethyl dioxirane as an oxidising agent is described in this study. The effects of several parameters, such as the concentration of the oxidising agent, the initial dye concentration, and the pH, have been investigated. At room temperature, the oxidising agent dimethyl dioxirane was employed to test the degradation of CR and NI dyes. On the degradation efficiency of CR and NI, pH’s effects, oxidising agent, and initial dye concentration were examined. The absorbance of CR and NI dyes before and after degradation was measured using UV-visible spectroscopy. The functional group existing in the dyes before and after degradation was determined using FT-IR spectroscopy.

scholarly journals Synthesis, characterization, electrochemical studies and X-ray structures of mixed-ligand polypyridyl copper(II) complexes with the acetate

2016 ◽  
Vol 81 (11) ◽  
pp. 1251-1262 ◽  
Author(s):  
Oluwafunmilayo Adekunle ◽  
Ray Butcher ◽  
Oladapo Bakare ◽  
Olusegun Odunola
Keyword(s):  
Room Temperature ◽  
Magnetic Measurements ◽  
Magnetic Moments ◽  
Copper Ion ◽  
X Ray Diffraction ◽  
Visible Spectroscopy ◽  
X Ray ◽  
Elemental Analyses ◽  
Structural Details ◽  
Uv Visible

[Cu(phen)2(CH3COO)](ClO4).2H2O (1) and [Cu(bipy)2(CH3COO)]-(ClO4).H2O (2) {phen = 1,10-phenanthroline, bipy = 2,2?-bipyridine}were synthesized and characterized. The complexes were characterized by employying elemental analyses, infrared and UV-Visible spectroscopy, room temperature magnetic measurements and the crystal structures elucidated using X-ray diffraction experiment. The redox properties of the complexes were also investigated. Both structures have a square pyramidal CuN4O chromophore which exhibit significant distortions due to long Cu-O [2.217(3) ? for (1) and 2.179 (1) for (2)] and Cu-N [2.631(2) ? for (1) and 2.714(1) ? for (2)] bonds. This distortion if further shown by the O-Cu-N bond angles [147.71(8) o for (1) and 153.40(5) o for (2)]. The elemental analyses further support the structural details unveiled by the single crystal X-ray diffraction analysis. The infrared spectra shows the acetate vibrational frequencies at 1587 cm-1,1428 cm-1, 1314 cm-1 for (1) and 1571 cm-1, 1441 cm-1, 1319c m-1 for (2) and the perchlo-rate bands at 1059 cm-1, 720 cm-1 (1) and 1080 cm-1,768 cm-1 (2). The broad d-d bands for the copper ion at 14,514 cm-1(1) and 14,535 cm-1(2) support the adoption of square pyramid geometries. The magnetic moments for the two complexes are 1.83 B.M for (1) and 1.72 B.M for (2). The peak to peak values of the two complexes show that the electrode reactions are quasi-reversibile with ?Ep = 0.023V (1) and 0.025V for (2). In both structures, there are ?-? intermolecular interactions in addition to hydrogen bonding between the units.

Spectroelectrochemical and ESR studies of highly substituted copper corroles

2004 ◽  
Vol 08 (10) ◽  
pp. 1236-1247 ◽  
Author(s):  
Zhongping Ou ◽  
Jianguo Shao ◽  
Hui Zhao ◽  
Kei Ohkubo ◽  
Ingar H. Wasbotten ◽  
...  
Keyword(s):  
Low Temperature ◽  
Thin Layer ◽  
Room Temperature ◽  
Strong Electron ◽  
Phenyl Rings ◽  
Uv Visible ◽  
Electron Donating Groups ◽  
Weak Electron

Electrochemical and spectroelectrochemical studies are presented for nine copper corroles with electron-withdrawing or electron-donating substituents on the three meso-phenyl rings of the compounds or on the eight β-pyrrole positions of the macrocycle. Up to three reversible oxidations can be seen for each Cu (III) corrole in CH 2 Cl 2 containing 0.1 M TBAP. Unlike the case of ( OEC ) Cu , no dimer is electrochemically detected upon the first oxidation of these compounds at room temperature. However, a dimer forms at low temperature (< -50°C) for compounds having strong electron-donating groups. Two reductions are observed for all nine corroles at low temperature in CH 2 Cl 2, 0.1 M TBAP, but only one reduction is detected at room temperature for four of these compounds which have weak electron-withdrawing or electron-donating groups. The neutral, reduced or oxidized Cu corroles were also characterized by thin-layer UV-visible spectroelectrochemistry and ESR. The resulting data indicates that eight of the nine neutral complexes contain a Cu (III) center while only one complex, [ Br 8( C 6 F 5)3 Cor ] Cu , exists in its Cu (II) form in CH 2 Cl 2 containing 0.2 M TBAP.

Light-Induced Structural Changes in the LOV2 Domain ofAdiantumPhytochrome3 Studied by Low-Temperature FTIR and UV−Visible Spectroscopy†

Biochemistry ◽  
2003 ◽  
Vol 42 (27) ◽  
pp. 8183-8191 ◽  
Author(s):  
Tatsuya Iwata ◽  
Dai Nozaki ◽  
Satoru Tokutomi ◽  
Takatoshi Kagawa ◽  
Masamitsu Wada ◽  
...  
Keyword(s):  
Low Temperature ◽  
Structural Changes ◽  
Visible Spectroscopy ◽  
Uv Visible
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