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POTENTIATION OF OXIDATIVE DAMAGE TO PROTEINS BY ULTRAVIOLET‐A AND PROTECTION BY ANTIOXIDANTS
Author(s) -
Hu MiaoLin,
Tappel Al L.
Publication year - 1992
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1992.tb02171.x
Subject(s) - chemistry , radical , hydroxyl radical , superoxide dismutase , singlet oxygen , dithiothreitol , biochemistry , glyceraldehyde , photochemistry , trypsin , enzyme , superoxide , protease , dehydrogenase , oxygen , organic chemistry
— We have studied the damage of alcohol dehydrogenase (ADH) and glyceraldehyde 3‐p‐hosphate dehydrogenase (GAPD) induced by Fe ++ /EDTA + H 2 O 2 in combination with UV‐A (main output at 365 nm). Enzyme inactivation, formation of hydroxyl radicals (measured in the absence of enzymes), increase in protein carbonyls, oxidation of sulfhydryl (SH) groups, loss of native protein fluorescence, and enhanced protease degradation were used to determine protein damage. Hydroxyl radical production was greatly enhanced by the combination of UV‐A with Fe ++ /EDTA + H 2 O 2 . The combined treatment increased protein carbonyls but decreased native protein fluorescence and SH groups. The combined treatment caused turbidity in GAPD but not in ADH, whereas trypsin susceptibility was increased more in ADH than in GAPD. These measurements of protein oxidation correlated well with enzyme activities. Glyceraldehyde 3‐p‐hosphate dehydrogenase and dithiothreitol were most protective against such damage, while hydroxyl radical and singlet oxygen scavengers were partially effective. Superoxide dismutase had no effect. Thus, UV‐A potentiation of protein damage induced by FE ++ /EDTA + H 2 O 2 appeared to involve hydroxyl radicals and perhaps singlet oxygen but not superoxide radicals. The damage to proteins induced by combination of UV‐A with physiological oxidants, iron ions and H z O 2 may be relevant to UV‐A‐induced skin and tissue damage.