Uv‐induced Protein Alterations and Lipid Oxidation in Erythrocyte Membranes

Abstract

Certain ultraviolet radiation-induced effects in skin may result from primary photochemical alterations in cell membranes. We have studied isolated erythrocyte membranes in order to determine the UV-fluence and wavelength dependence for protein alterations and lipid oxidation. Protein crosslinking was detected as high molecular weight protein (greater than 200,000 DA) on polyacrylamide/agarose gel electrophoresis. Spectrin decreased more rapidly than the other membrane proteins upon exposure to lambda = 250-380 nm radiation. Nitrogen-purging inhibited the UV-induced decrease in spectrin by 60% and decreased crosslinking to an even greater degree. The decrease in spectrin was not inhibited by superoxide dismutase, catalase, or sodium azide. Radiation at 280 nm was most effective for spectrin loss, 265 and 297 nm were less effective and 254 and 313 nm were not effective. Prior irradiation at 280 nm did not sensitize the membranes to subsequent irradiation at 313 nm indicating that photodecomposition products of tryptophan are not involved. Lipid photooxidation was measured with the thiobarbituric acid assay and was induced at higher fluences of UV radiations than those required for loss of spectrin. These results indicate that the major effects of UV radiation on cell membranes are alterations of proteins and suggest that tryptophan is the major chromophore for these alterations.

In Vivo Photomodification of Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase Holoenzyme by Ultraviolet-B Radiation (Formation of a 66-Kilodalton Variant of the Large Subunit)

“…Photooxidation of proteins induced by UV-B radiation has been studied by monitoring changes in enzyme activity, protein profiles, or Trp fluorescence (Grossweiner et al, 1976;Fujimori, 1981;Grossweiner, 1984;Imbrie and Murphy, 1984;Gerard, 1984, 1989;Greenberg et al, 1989;Kochevar, 1990;Caldwell, 1993). Although other chromophores in proteins can trigger oxidative damage following absorbance of a UV-B photon, in Rubisco there are no UV-B-absorbing cofactors and Trp is the only amino acid that absorbs in the range of UV-B radiation used in this study (<292 nm) (Grossweiner et al, 1976;Gerard, 1984, 1989;Kochevar, 1990;Kim and Sancar, 1993).…”

“…Although other chromophores in proteins can trigger oxidative damage following absorbance of a UV-B photon, in Rubisco there are no UV-B-absorbing cofactors and Trp is the only amino acid that absorbs in the range of UV-B radiation used in this study (<292 nm) (Grossweiner et al, 1976;Gerard, 1984, 1989;Kochevar, 1990;Kim and Sancar, 1993). After Trp absorbs a UV photon and reaches an excited state, it can undergo intersystem crossing to form a triplet state, and subsequently the absorbed energy can be passed to O,, forming singlet oxygen ('Oz).…”

“…Trp can also be photooxidized to the Trpf radical cation (Grossweiner, 1984). Radical cation formation can result in the direct intramolecular transfer of electrons from Trp to a nearby amino acid residue (Pigault and Gerard, 1989;Kochevar, 1990). These reactions may result in covalent cross-linking between residues and / or direct damage to residues in close proximity to the Trp.…”

R3DE: Radiation Risk Radiometer-Dosimeter on the International Space Station—Optical Radiation Data Recorded During 18 Months of EXPOSE-E Exposure to Open Space

“…Without protection, UVB and UVC strongly impact living organisms. The wavelength range of about 280 nm has the most deleterious impact on proteins, and radiation of about 265 nm exhibits maximal effects on DNA/RNA (Kochevar, 1990;Gerber and Hä der, 1992). In addition, damage of various other biomolecules due to photochemical reactions as well as oxidative …”

Advances in Crop Responses to Enhanced Uv-B Radiation

“…Ultraviolet radiation has been shown to be very effective in inducing lipid oxidation of biological membranes (Kochevar, 1990;Foyer et al, 1994), polyunsaturated fatty acids (Yamashoji et al, 1979) and phospholipid liposomes (Pelle et al, 1990). There is a considerable amount of data that demonstrates ways in which UV radiation alters membrane structure or function: changes in membrane permeability, inhibited K-ATPase and peroxidized lipids in wheat (Triticum aestivum) Wright et al, 1981) and decreased membrane resistance in Chara coralline (Doughty and Hope, 1973).…”