Effect of oxygen on the radiolysis of tyrosine in aqueous solutions
The effect of oxygen on the radiolysis of tyrosine in aqueous solutions was investigated by using gamma and pulsed electron irradiation. Steady-state radiolysis was reexamined and extended to include the effect of pH and determination of hydrogen peroxide. The loss of tyrosine, G(-Tyr), during irradiation and yields of 3,4-dihydroxyphenylalanine, G(DOPA), and hydrogen peroxide, G(H2O2), are determined in the pH range from 1 to 9. In the whole pH range used G(-Tyr) equals G(DOPA), and a higher G(H2O2) than expected was observed. In slightly acid and neutral media, both G(-Tyr) and G(DOPA) equal the yield of hydroxyl radicals, GOH, formed in the radiolysis of water, while the excess of hydrogen peroxide equals 1/2 GOH. Hence it was concluded that all tyrosine OH-adducts react with oxygen yielding peroxy radicals. In acid and alkaline media all measured yields decrease. This is caused by formation of tyrosine phenoxyl radicals (TyrO), which react with superoxide anion (O2-) and hydroperoxy (HO2) radicals regenerating tyrosine. By using pulse radiolysis K(TyrO + O2) less than or equal to 2 X 10(5) mol-1 dm3 s-1 and k(TyrO + O2-) = (1.7 +/- 0.2) X 10(9) mol-1 dm3 s-1 were determined. On the basis of the results, a reaction mechanism is proposed.
- Research Organization:
- Boris Kidric Institute of Nuclear Sciences-Vinca, Beograd, Yugoslavia
- OSTI ID:
- 6695285
- Journal Information:
- Radiat. Res.; (United States), Vol. 2
- Country of Publication:
- United States
- Language:
- English
Similar Records
The effect of oxygen, antioxidants, and superoxide radical on tyrosine phenoxyl radical dimerization
The radiation induced chemistry of uranyl cation in aqueous carbonate –bicarbonate solutions as followed by NMR spectroscopy
Related Subjects
TYROSINE
RADIOLYSIS
DOPA
ELECTRONS
GAMMA RADIATION
HYDROGEN PEROXIDE
OXYGEN
AMINO ACIDS
AUTONOMIC NERVOUS SYSTEM AGENTS
CARBOXYLIC ACIDS
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
CHEMISTRY
DECOMPOSITION
DRUGS
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
ELEMENTS
FERMIONS
HYDROGEN COMPOUNDS
HYDROXY ACIDS
IONIZING RADIATIONS
LEPTONS
NEUROREGULATORS
NONMETALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PEROXIDES
RADIATION CHEMISTRY
RADIATION EFFECTS
RADIATIONS
560120* - Radiation Effects on Biochemicals
Cells
& Tissue Culture