title: Zinc-metallothionein protects from DNA damage induced by radiation better than glutathione and copper- or cadmium-metallothioneins.
abstract: Protection of radiation-induced DNA damage by metallothionein (MT) has been documented, but there is no detailed information about its efficiency compared to other antioxidants or the effect of metals which bind to MT on the protective effect of MT in radiation-induced DNA damage. In this study, we used a cell-free system to investigate the effect of MT with other antioxidants, such as albumin and glutathione and we compared the efficiency of MT bound to different metals on radiation-induced DNA damage. DNA damage was measured by loss in ethidium bromide/DNA fluorescence and increased mobility of DNA on gel electrophoresis. Gamma rays at 30 Gy induced significant DNA damage and zinc-MT showed a significant higher protection from radiation-induced DNA damage than both glutathione and albumin. Metallothionein bound to other metals, such as copper and cadmium, also showed protection of radiation-induced DNA damage, but the protective effect by zinc-MT was the highest. These results suggest that MT, in particular bound to zinc, is a high-capacity antioxidant to protect radiation-induced DNA damage.
authors.affiliation: Department of Pathology, University of Western Ontario, London, Ont., Canada N6A5C1. l0cai001@gwise.louisville.edu
authors.forename: Lu
authors.initials: L
authors.lastname: Cai
authors.forename: M George
authors.initials: MG
authors.lastname: Cherian
mesh_terms: D000975:Antioxidants / Q000494:pharmacology; D002474:Cell-Free System; D004247:DNA / Q000737:chemistry / Q000187:drug effects / Q000528:radiation effects; D004249:DNA Damage / Q000187:drug effects* / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D004587:Electrophoresis, Agar Gel; D005720:Gamma Rays; D005978:Glutathione / Q000494:pharmacology*; D008668:Metallothionein / Q000494:pharmacology*; D011830:Radiation Effects; D011837:Radiation-Protective Agents
chemical_list: D000975:Antioxidants; D011837:Radiation-Protective Agents; C004203:cadmium-binding protein; C007121:copper thionein; C021267:zinc thionein; D004247:DNA; D008668:Metallothionein; D005978:Glutathione