scholarly journals RESPIRATION AND PROTEIN SYNTHESIS IN ESCHERICHIA COLI MEMBRANE-ENVELOPE FRAGMENTS

1971 ◽  
Vol 51 (3) ◽  
pp. 664-673 ◽  
Author(s):  
Richard W. Hendler
Keyword(s):  
Escherichia Coli ◽  
Nadh Oxidase ◽  
Protein Complexes ◽  
Nonheme Iron ◽  
Paramagnetic Resonance ◽  
Iron Protein ◽  
Membrane Envelope ◽  
Epr Signal ◽  
Almost All ◽  
Electron Paramagnetic

The sensitivity of nicotinamide adenine dinucleotide (NADH) oxidase and succinoxidase to metal chelators, the generation of an electron paramagnetic resonance (EPR) signal upon addition of these substrates, and the rate of formation of the EPR signal relative to the rate of the cytochrome reduction suggest the participation of nonheme iron proteins in the respiratory process of Escherichia coli. The most inhibitory metal chelator, thenoyltrifluoro acetone, inhibited the reduction of nonheme iron and cytochromes but did not prevent the reoxidation of the reduced forms. The EPR signal, dehydrogenase, and oxidase activities evoked by NADH are considerably greater than the corresponding activities evoked by succinate. Because both substrates can reduce almost all of the cytochromes, a model in which fewer succinate dehydrogenase-nonheme iron protein complexes are linked to a common cytochrome chain than NADH dehydrogenase-nonheme iron protein complexes is considered likely.

Site of action of nonheme iron in the malate (flavine adenine dinucleotide) pathway of Mycobacterium phlei

1976 ◽  
Vol 22 (7) ◽  
pp. 1054-1057 ◽  
Author(s):  
A. K. Tyagi ◽  
T. L. Prasada Reddy ◽  
T. A. Venkitasubramanian
Keyword(s):  
Electron Transport ◽  
Ultraviolet Light ◽  
Nonheme Iron ◽  
Paramagnetic Resonance ◽  
Iron Protein ◽  
Mycobacterium Phlei ◽  
Diphenyl Tetrazolium Bromide ◽  
Electron Paramagnetic ◽  
Soluble Components ◽  
Malate Oxidation

Irradiation with ultraviolet light (360 nm) of cell-free extracts, electron-transport particles, and soluble components from Mycobacterium phlei resulted in the loss of malate oxidation by the flavine adenine dinucleotide pathway both in cell-free extracts and reconstituted systems. Addition of vitamin K1 restored the loss to the extent of 14% and 11% in cell-free extracts and reconstituted systems respectively. Electron-transport particles from M. phlei upon reduction with malate exhibited electron-paramagnetic resonance signals at g = 2.002 and 1.94, characteristic of napthosemiquinone and nonheme iron protein, respectively. Upon irradiating the particles with ultraviolet light (360 nm) these signals were not observed. Particulate flavine-adenine-dinucleotide-dependent malate dehydrogenase (EC 1.1.1.37) of M. phlei assayed by the 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyl tetrazolium bromide and phenazine methosulfate–2,6-dichlorophenolindophenol systems, which trap electrons at cytochrome c and at the flavine level respectively, was inhibited by o-phenanthroline. These observations suggest that nonheme iron protein is sensitive to ultraviolet light (360 nm) and participates before or in combination with flavine in the malate (flavine adenine dinucleotide) pathway of M. phlei.

Selective spin-labeling of the ribosomal proteins of 70S ribosomes from Escherichia coli

1979 ◽  
Vol 57 (12) ◽  
pp. 1407-1415 ◽  
Author(s):  
H. Dugas ◽  
A. Rodriguez ◽  
N. Brisson
Keyword(s):  
Escherichia Coli ◽  
Ribosomal Proteins ◽  
Spin Labeling ◽  
Spin Labels ◽  
Magnesium Ions ◽  
Nitroxide Group ◽  
Paramagnetic Resonance ◽  
Long Period ◽  
Epr Signal ◽  
Electron Paramagnetic

We have used a series of N-(1-oxyl-2,2,5,5-tetramethyl-3-pyrrolidinyl) maleimide spin labels of different length to label, covalently and selectively, the most reactive sulfhydryl groups of 70S ribosomal proteins of Escherichia coli. Under short periods of labeling (1–2 min), less than two spin labels per ribosome are incorporated and were shown to be distributed mainly on five ribosomal proteins in the following order: S18 > S21, L27 > S17, and S12. With a long period of labeling (3 h) up to 13 spin labels are attached to the ribosome, and protein S1 is the most labeled. The shape of the electron paramagnetic resonance (epr) signal shows two components with a predominance for the strongly immobilized orientation, and the percentage of these components in each spectra has been evaluated. When the distance between the nitroxide group and the maleimide-attaching group exceeds 6 Å (1 Å = 0.1 nm) the strongly immobilized orientation disappears. The effect of magnesium ions on these selectively spin-labeled ribosomes shows that the dissociation into subunits does not affect the epr signal, but more spin labels are incorporated into the subunits if labeling is performed under conditions of dissociation.

Room Temperature Electron Paramagnetic Resonance (EPR) Signal Storage

1969 ◽  
Author(s):  
D.A. Bozanic ◽  
D.C. Buck ◽  
F.H. Harris ◽  
R.E. Huber ◽  
D. Mergerian ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Room Temperature ◽  
Paramagnetic Resonance ◽  
Temperature Electron ◽  
Epr Signal ◽  
Electron Paramagnetic

scholarly journals Simulation of the electron-paramagnetic-resonance spectrum of the iron-protein of nitrogenase. A prediction of the existence of a second paramagnetic centre

1978 ◽  
Vol 175 (3) ◽  
pp. 955-957 ◽  
Author(s):  
D J Lowe
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Electron Paramagnetic Resonance Spectrum ◽  
Complex Formation ◽  
Resonance Spectrum ◽  
The Other ◽  
Paramagnetic Centre ◽  
Paramagnetic Resonance ◽  
Iron Protein ◽  
Integrated Intensities ◽  
Electron Paramagnetic

The e.p.r. spectra of the Fe-proteins of nitrogenase from all sources studied have unusual features in that they have very anisotropic linewidths and low integrated intensities. These characteristics can be explained by assuming that one of the two electrons accepted by these proteins is located at a rapidly relaxing paramagnetic centre that is unobservable by e.p.r., but causes anisotropic broadening of the e.p.r. signal of the other electron. Complex-formation between Fe-proteins and MgATP is described in terms of a 50-60 degrees rotation of the e.p.r.-observable centre.

Partial dissociation of nitrogen aggregates in diamond by high temperature-high pressure treatments

1978 ◽  
Vol 361 (1704) ◽  
pp. 109-127 ◽  
Keyword(s):  
General Relation ◽  
Infrared Region ◽  
Optical Measurements ◽  
Type I ◽  
Paramagnetic Resonance ◽  
High Concentrations ◽  
Partial Dissociation ◽  
Almost All ◽  
Electron Paramagnetic

Type I (a) diamonds contain high concentrations of nitrogen, almost all of which is in an aggregated form. The two main aggregates are recognized by characteristic absorption features in the infrared region of the spectrum. These are called A and B features; usually a peak designated B' is also present. When such diamonds were heated at 1960 °C and above under a stabilizing pressure of 85kbar (8.5 GPa) the nitrogen aggregates partially dissociated, producing single substitutional atoms which were identified by electron paramagnetic resonance (e.p.r.) measurements. Experiments with selected diamonds, showing wide variations in their characteristic infrared absorption, determined the relative stability of the A and B centres. Optical measurements led to the determination of a general relation between the strengths of the A, B and B' features. The experimental observations suggest a scheme for the occurrence of type I (a) diamonds containing nitrogen atoms which have aggregated into A centres; type I (b) diamonds can also be included in this scheme.

Evaluation of systemic blood NO dynamics by EPR spectroscopy: HbNO as an endogenous index of NO

2003 ◽  
Vol 285 (2) ◽  
pp. H589-H596 ◽  
Author(s):  
Kazuyoshi Kirima ◽  
Koichiro Tsuchiya ◽  
Hiroyoshi Sei ◽  
Toyoshi Hasegawa ◽  
Michiyo Shikishima ◽  
...  
Keyword(s):  
Endothelial Dysfunction ◽  
Whole Blood ◽  
Computer Assisted ◽  
Subtraction Method ◽  
Epr Spectrum ◽  
Systemic Blood ◽  
Paramagnetic Resonance ◽  
Species Overlap ◽  
Epr Signal ◽  
Electron Paramagnetic

The measurement of hemoglobin-nitric oxide (NO) adduct (HbNO) in whole blood by the electron paramagnetic resonance (EPR) method seems relevant for the assessment of systemic NO levels. However, ceruloplasmin and unknown radical species overlap the same magnetic field as that of HbNO. To reveal the EPR spectrum of HbNO, we then introduced the EPR signal subtraction method, which is based on the computer-assisted subtraction of the digitized EPR spectrum of HbNO-depleted blood from that of sample blood using the software. Rats were treated with Nω-nitro-l-arginine methyl ester (l-NAME; 120 mg · kg–1 · day–1) for 1 wk to obtain HbNO-depleted blood. When this method was applied to the analysis of untreated fresh whole blood, the five-coordinate state of HbNO was observed. HbNO concentration in pentobarbital-anesthetized rats was augmented (change in [HbNO] = 1.6–5.5 μM) by infusion of l-arginine (0.2–0.6 g/kg) but not d-arginine. Using this method, we attempted to evaluate the effects of temocapril on HbNO dynamics in an l-NAME-induced rat endothelial dysfunction model. The oral administration of l-NAME for 2 wk induced a serious hypertension, and the HbNO concentration was reduced (change in [HbNO] = 5.7 μM). Coadministration of temocapril dose dependently improved both changes in blood pressure and the systemic HbNO concentration. In this study, we succeeded in measuring the blood HbNO level as an index of NO by the EPR HbNO signal subtraction method. We also demonstrated that temocapril improves abnormalities of NO dynamics in l-NAME-induced endothelial dysfunction rats using the EPR HbNO signal subtraction method.

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