Perturbations of Simple Oscillations and Complex Dynamics in the Peroxidase−Oxidase Reaction Using Magnetic Fields

and, Ane Christine Møller; Olsen, Lars Folke

doi:10.1021/jp993284m

Cited by 20 publications

(11 citation statements)

References 27 publications

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“…Experiments were conducted as described previously [22,23] at 28 (± 0.1) °C in a 2.0 × 2.0 × 4.3 cm 3 quartz cuvette fitted with a thermostating jacket. The cuvette was connected to a Zeiss S10 diode array spectrophotometer through optical fibers.…”

Section: Methodsmentioning

confidence: 99%

Mechanism of protection of peroxidase activity by oscillatory dynamics

Olsen

Hauser

Kummer

2003

European Journal of Biochemistry

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The peroxidase-oxidase reaction is known to involve reactive oxygen species as intermediates. These intermediates inactivate many types of biomolecules, including peroxidase itself. Previously, we have shown that oscillatory dynamics in the peroxidase-oxidase reaction seem to protect the enzyme from inactivation. It was suggested that this is due to a lower average concentration of reactive oxygen species in the oscillatory state compared to the steady state. Here, we studied the peroxidase-oxidase reaction with either 4-hydroxybenzoic acid or melatonin as cofactors. We show that the protective effect of oscillatory dynamics is present in both cases. We also found that the enzyme degradation depends on the concentration of the cofactor and on the pH of the reaction mixture. We simulated the oscillatory behaviour, including the oscillation/steady state bistability observed experimentally, using a detailed reaction scheme. The computational results confirm the hypothesis that protection is due to lower average concentrations of superoxide radical during oscillations. They also show that the shape of the oscillations changes with increasing cofactor concentration resulting in a further decrease in the average concentration of radicals. We therefore hypothesize that the protective effect of oscillatory dynamics is a general effect in this system. Keywords: peroxidase; superoxide radical; hydrogen peroxide; oscillations; enzyme degradation.Within the last 30 years the number of reports on oscillating biochemical processes has grown considerably [1]. From the first observations of oscillations in glycolysis in yeast and muscle cells [2,3] through measurements of oscillations in secondary messengers such as cyclic AMP [4] and cytosolic Ca 2+ [5] to recent observations of oscillations in intracellular NAD(P)H, pH, hydrogen peroxide, and superoxide in migrating neutrophils [6,7] we are beginning to understand that temporal behaviours, that is dynamics, play important roles in cell metabolism. Thus, it might be appropriate to suggest that in addition to its genome and proteome a given cell should also be characterized by the diversity of its dynamic behaviours.In spite of their universal occurrence the functions of metabolic oscillations in cells are still not well understood. It is not certain whether some biochemical oscillations occur as harmless side-effects of the nonlinear properties of metabolic enzymes or whether they always serve one or more important functions. Over the years many different roles have been proposed for oscillations. It has been suggested that they provide metabolism with an increased thermodynamic efficiency [8]. Furthermore, oscillations, e.g. those of second messengers such as calcium ions, are believed to have information stored in their frequency [9]. Roles as biological time-keepers [1] and encoders of transmembrane signalling have also been proposed [10]. Presumably, oscillations serve many functions in cell metabolism. Here we wish to explore further another potential role of oscillating...

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Section: Methodsmentioning

confidence: 99%

Mechanism of protection of peroxidase activity by oscillatory dynamics

Olsen

Hauser

Kummer

2003

European Journal of Biochemistry

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“…The final amplification mechanism (m) is more speculative (giving, perhaps, greater scope for disproportionate enhancements of ELF magnetic field effects). It requires a reaction scheme involving chemical feedback in which a radical pair is one of the key reaction intermediates (81)(82)(83)(84)(85)(86)(87). The inherent non-linearity of such reactions could at least in principle allow small magnetically induced changes in radical pair lifetimes to have a disproportionately large effect on, for example, the amplitude of chemical oscillations.…”

Section: (E)mentioning

confidence: 99%

Upper bound on the biological effects of 50/60 Hz magnetic fields mediated by radical pairs

Hore

2018

Preprint

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Prolonged exposure to weak (~1 T) extremely-low-frequency (ELF, 50/60 Hz) magnetic fields has been associated with an increased risk of childhood leukaemia. One of the few biophysical mechanisms that might account for this link involves short-lived chemical reaction intermediates known as radical pairs. In this report, we use spin dynamics simulations to derive an upper bound of 10 parts per million on the effect of a 1 T ELF magnetic field on the yield of a radical pair reaction. By comparing this figure with the corresponding effects of changes in the strength of the Earth's magnetic field, we conclude that if exposure to such weak 50/60 Hz magnetic fields has any effect on human biology, and results from a radical pair mechanism, then the risk should be no greater than travelling a few kilometres towards or away from the geomagnetic north or south pole.

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“…Changes in the external environment of an oscillatory chemical reaction by application of electric field, magnetic field, or light can be used to control its dynamics [13][14][15]. Control can also be achieved internally by performing the reaction in the presence of nonreacting chemical species such as micelles [16][17][18][19] known to affect chemical equilibria and reactivities [20,21] by selectively sequestering the reagent substrates by means of electrostatic and hydrophobic interactions.…”

Section: Introductionmentioning

confidence: 99%

Effect of self-assemblies of various surfactants in their single and mixed states on the BZ oscillatory reaction

Najar¹,

Dar²,

Rather³

2010

Int. J. Chem. Kinet.

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Micelles of different surfactants are well known to affect chemical equilibria and reactivities by selectively sequestering the reagent substrates through electrostatic and hydrophobic interactions. In this article, the effects of micelles of various surfactants on different parameters of the Ce(IV)-catalyzed Belousov-Zhabotinsky (BZ) oscillatory reaction at 35 • C in nonstirred closed conditions are studied by employing spectrophotometry and tensiometry. Surfactants used in this study are the cationics hexadecyltrimethylammonium bromide (CTAB) and pentamethylene-1,5-bis(N-hexadecyl-N,N-dimethylammonium)bromide gemini (Gemini), anionic sodium dodecylbenzene sulfonate (SDBS), and nonionic Brij58, whereas the binary surfactant systems used are cationic-nonionic CTAB+Brij58 and anionic-nonionic SDBS+Brij58. The results revealed that the induction period shows a definite variation with increasing concentration of different surfactants above their critical micelle concentration (cmc). The amplitudes of oscillation and absorbance maxima and minima are enhanced in the presence of micelles of CTAB and Gemini surfactants, whereas micelles of SDBS and Brij58 have almost no effect on the nature of the oscillations. However, mixed micelles of CTAB+Brij58 and SDBS+Brij58 binary mixtures show a quite different effect on the overall behavior of the oscillations. The enhanced effect of CTAB and Gemini surfactants on the overall nature of oscillations has been attributed to the positive charge on the surface of their micelles and to some extent on the presence of nitrogen in their head group. The effect of mixed binary micelles may be attributed to their synergistic nature. C 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: [659][660][661][662][663][664][665][666][667][668] 2010

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Perturbations of Simple Oscillations and Complex Dynamics in the Peroxidase−Oxidase Reaction Using Magnetic Fields

Cited by 20 publications

References 27 publications

Mechanism of protection of peroxidase activity by oscillatory dynamics

Mechanism of protection of peroxidase activity by oscillatory dynamics

Upper bound on the biological effects of 50/60 Hz magnetic fields mediated by radical pairs

Effect of self-assemblies of various surfactants in their single and mixed states on the BZ oscillatory reaction

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