• BMB Reports
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• v.31 no.2
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• pp.161-169
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• 1998

TThe reactive oxygen species oxidatively modify the biological macromolecules, including proteins, lipids, and nucleic acids. Iron- and heme-mediated Fenton-like reactions produce different pro-oxidants. However, these reactive products have not been clearly characterized. We examined the nature of the oxidizing species from the different iron sources by measuring oxidative protein modification and spectroscopic study. Hemoglobin (Hb) and methemoglobin (metHb) were oxidatively modified in $O{\array-\\\dot{2}}$ and $H_{2}O_{2}$ generating systems. Globin and bovine serum albumin (BSA) were also modified by iron, iron-EDTA, hematin, and Hb in an $O{\array-\\\dot{2}}$ generating system. In a $H_{2}O_{2}$ generating system, the iron- and iron-EDTA-mediated protein modifications were markedly reduced while the Hb-and hematin-mediated modifications were slightly increased. In the $O{\array-\\\dot{2}}$ generating system, the iron- and iron-EDTA-mediated protein modifications were strongly inhibited by superoxide dismutase (SOD) or catalase, but heme- and Hb-mediated protein modifications were inhibited only by catalase and slightly increased by SOD. Mannitol, 5,5-dimethyl-l-pyrroline-N-oxide (DMPO), deoxyribose, and thiourea inhibited the iron-EDTA-mediated protein modification. Mannitol and DMPO, however, did not exhibit significant inhibition in the hematin-mediated modification. Desferrioxamine (DFO) inhibited protein modification mediated by iron, but cyanide and azide did not, while the hematin-mediated protein modification was inhibited by cyanide and azide, but not significantly by DFO. The protein-modified products by iron and heme were different. ESR and UV-visible spectroscopy detected the DMPO spin adduct of the hydroxyl radical and ferryl ion generated from iron-EDTA and metHb, respectively. These results led us to conclude that the main oxidizing species are hydroxyl radical in the iron-EDTA type and the ferry I ion in the hematin type, the latter being more effective for protein modification.

• The Korean Journal of Pesticide Science
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• v.6 no.1
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• pp.16-24
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• 2002

Research trends in the measurement of foliar uptake of pesticides and the recently proposed action mechanism of the surfactant-induced uptake of pesticides were reviewed with the related reports and studies. Major techniques used in those fields are bioassay, radiotracer techniques with leaves or cuticular membrane. Recently, a new method using Congo Red as a tracer was proposed. The limiting factor in the pesticides uptake into leaves is the waxy layer which consists of the epicuticular and cuticular wax. Physico-chemical parameters such as molar volume, water solubility and partition coefficient of pesticides have limited influences on the pesticide uptake into leaves. Polydisperse ethoxylated fatty alcohol surfactants are well known as the good activator for many pesticides. It is now generally agreed that uptake activation is not related to the intrinsic surface active properties of surfactants such as surface activity, solvent property, humectancy and critical micelle concentration. Recent studies using ESR-spectroscopy revealed that the surfactants have an unspecific plasticising effect on the molecular structure of the wax and cuticular matrix, leading to increased mobilities of pesticides. Penetration of surfactants into waxy layer altered the pesticide mobility in wax and the partition coefficient of pesticide, and then the pesticides penetration into leaves was enhanced temporally. The enhancing effect of surfactant could be significantly different depending on the carbon number of aliphatic moiety and the number of ethoxy group in polyoxyethylene chain of surfactants. It is suggested that the rate of penetration of surfactants should have a significant relationship with the rate of penetration of pesticides.