The Oxygen Effect in Radiation Inactivation of DNA and Enzymes

Quintiliani, M.

doi:10.1080/09553008614550981

Cited by 99 publications

(41 citation statements)

References 38 publications

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“…Thus, to better understand the damaging effects of LEE on DNA, attempts have been made to perform LEE-irradiation experiments under conditions more closely approximating those found in the cell. For this reason, the effect of water and oxygen molecules on radiationinduced damage in biological systems has been extensively studied (Yokoya et al, 2002;Quintiliani, 1986;Yokoya et al 2009;Alizadeh et al 2011). Also in our laboratory some experiments have been completed under well-controlled environmental conditions at standard atmospheric temperature and pressure (STP) to show the induction of DNA damage by LEEs in presence of gases such as, air, pure N 2 and O 2 .…”

Section: Introductionmentioning

confidence: 99%

Induction of strand breaks in DNA films by low energy electrons and soft X-ray under nitrous oxide atmosphere

Alizadeh

Sanche

2012

Radiation Physics and Chemistry

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Five-monolayer (5ML) plasmid DNA films deposited on glass and tantalum substrates were exposed to Al K α X-rays of 1.5 keV under gaseous nitrous oxide (N 2 O) at atmospheric pressure and temperature. Whereas the damage yields for DNA deposited on glass are due to soft X-rays, those arising from DNA on tantalum are due to both the interaction of low energy photoelectrons from the metal and X-rays. Then, the differences in the yields of damage on glass and tantalum substrates, essentially arises from interaction of essentially low-energy electrons (LEEs) with DNA molecules and the surrounding atmosphere. The G-values (i.e., the number of moles of product per Joule of energy absorbed) for DNA strand breaks induced by LEEs (G LEE ) and the lower limit of G-values for soft X-ray photons (G XL ) were calculated and the results compared to those from previous studies under atmospheric conditions and other ambient gases, such as N 2 and O 2 . Under N 2 O, the G-values for loss of supercoiled DNA are 103±15 nmol/J for X-rays, and 737±110 nmol/J for LEEs. Compared to corresponding values in an O 2 atmosphere, the effectiveness of X-rays to damage DNA in N 2 O is less, but the G value for LEEs in N 2 O is more than twice the corresponding value for an oxygenated environment. This result indicates a higher effectiveness for LEEs relative to N 2 and O 2 environments in causing SSB and DSB in an N 2 O environment. Thus, the previously observed radiosensitization of cells by N 2 O may not be only due to OH • radicals but also to the reaction of LEE with N 2 O molecules near DNA. The previous experiments with N 2 and O 2 and the present one demonstrate the possibility to investigate damage induced by LEEs to biomolecules under various type of surrounding atmospheres.

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Section: Introductionmentioning

confidence: 99%

Induction of strand breaks in DNA films by low energy electrons and soft X-ray under nitrous oxide atmosphere

Alizadeh

Sanche

2012

Radiation Physics and Chemistry

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“…The rate of destruction is practically independent of temperature during the treatment of enzyme preparation with radiations. Perhaps, it is affected by pH and chemical conditions like presence of substrate, optical sensitizers and oxygen [17,18]. While enzymes are very stable to heat inactivation near their optimal pH, the reverse is often the case with regard to ultraviolet (UV) radiations.…”

Section: Action Of Radiations On Enzymementioning

confidence: 99%

Kinetic Modelling of Enzyme Catalyzed Biotransformation Involving Activations and Inhibitions

Yadav¹,

Magadum²

2017

Enzyme Inhibitors and Activators

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To achieve transition from lab scale enzyme studies to industrial applications, understanding of enzyme kinetics plays a critical role. The widely applied Michaelis Menten equation of the single substrate kinetics, sequential and double replacement mechanism of bisubstrate reaction and the relevant kinetics, inhibition and activation of enzyme are all integral parts of this discussion. In this chapter, we have discussed different types of inhibition and kinetic modelling. Systematic approach to generate data and its interpretation as well as designing of inhibitors is also explained.

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“…Radiation toxicity is thought to be elicited from reactive oxygen species (ROS) generated by the interaction between water molecules and ionizing radiation in living cells [1][2][3][4] . ROS include O2 − , H2O2 , and OH, et al, and are readily generated in cells through metabolic processes such as respiration, ischemia/reperfusion, and oxidation of fatty acids, other than a radiolysis of the water.…”

Section: Introductionmentioning

confidence: 99%

ATP Released from Low-dose Gamma Ray-irradiated Cells Activates Intracellular Antioxidant Systems via Purine Receptors

2011

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Antioxidants are known to prevent oxidative damage in cells caused by radiation. We have previously reported that whole-body irradiation with low doses of gamma rays to mice elevates the antioxidant thioredoxin-1 (Trx-1) levels in several organs. Furthermore, gamma ray irradiation also causes ATP release from the exposed cells. Extracellular ATP release in response to various stimuli has been reported to regulate the expression of intracellular antioxidants through activation of purinergic P2 receptors.Here, we review the relation between gamma-radiation-induced ATP release and the induction of cellular Trx-1 via purinergic signaling. Irradiation with gamma rays or exogenously adding ATP cause an increase in Trx-1 expression, and these phenomena disappear in the presence of an ecto-nucleotidase. Further, it is revealed that ATP generates intracellular reactive oxygen species (ROS), and thereby increases Trx-1 expression as an adaptive response to ROS.These findings suggest that gamma-radiation-induced release of extracellular ATP may contribute to the production of ROS via purinergic signaling, thereby leading to the promotion of intracellular antioxidants in response to an oxidative stress.

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The Oxygen Effect in Radiation Inactivation of DNA and Enzymes

Cited by 99 publications

References 38 publications

Induction of strand breaks in DNA films by low energy electrons and soft X-ray under nitrous oxide atmosphere

Induction of strand breaks in DNA films by low energy electrons and soft X-ray under nitrous oxide atmosphere

Kinetic Modelling of Enzyme Catalyzed Biotransformation Involving Activations and Inhibitions

ATP Released from Low-dose Gamma Ray-irradiated Cells Activates Intracellular Antioxidant Systems via Purine Receptors

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