title: Iron-sulfur centers as endogenous blue light sensitizers in cells: a study with an artificial non-heme iron protein.
abstract: The possible involvement of Fe-S clusters in photodynamic reactions as endogenous sensitizing chromophores in cells has been investigated, by using an artificial non-heme iron protein (ANHIP) derived from bovine serum albumin and ferredoxins isolated from spinach and a red marine algae. Ferredoxins and ANHIP, when exposed to visible light, generate singlet oxygen, as measured by the imidazole plus RNO method. Irradiation with intense blue light of the ANHIP-entrapped liposomes caused severe membrane-damage such as liposomal lysis and lipid peroxidation. In the presence of ANHIP, isocitrate dehydrogenase and fructose-1,6-diphosphatase were photoinactivated by blue light. However, all of these photosensitized reactions were significantly suppressed by a singlet oxygen (1O2) quencher, azide, but enhanced by a medium containing deuterium oxide. Further, the Fe-S proteins with the prosthetic groups destroyed did not initiate the blue light-induced reactions. In addition, the action spectrum for 1O2 generation from ANHIP was very similar to the visible absorption spectrum of Fe-S centers. The results obtained in this investigation appear consistent with the suggestion that Fe-S centers are involved in photosensitization in cells via a singlet oxygen mechanism.
authors.affiliation: Department of Agricultural Chemistry, Seoul National University, Suwon, Korea.
authors.forename: C S
authors.initials: CS
authors.lastname: Kim
authors.forename: J
authors.initials: J
authors.lastname: Jung
mesh_terms: D000818:Animals; D002417:Cattle; D066298:In Vitro Techniques; D007506:Iron-Sulfur Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000528:radiation effects*; D008081:Liposomes; D008667:Metalloproteins / Q000737:chemistry / Q000302:isolation & purification / Q000528:radiation effects*; D019159:Nonheme Iron Proteins; D010100:Oxygen / Q000528:radiation effects; D010777:Photochemistry; D011838:Radiation-Sensitizing Agents / Q000737:chemistry; D012710:Serum Albumin, Bovine / Q000737:chemistry / Q000528:radiation effects; D026082:Singlet Oxygen
chemical_list: D007506:Iron-Sulfur Proteins; D008081:Liposomes; D008667:Metalloproteins; D019159:Nonheme Iron Proteins; D011838:Radiation-Sensitizing Agents; D026082:Singlet Oxygen; D012710:Serum Albumin, Bovine; D010100:Oxygen