title: Quenching of singlet oxygen by biomolecules from L1210 leukemia cells.
abstract: Singlet oxygen lifetimes for detergent-dispersed L1210 leukemia cells in deuterium oxide buffer were measured by following the decay of 1270 nm phosphorescence. Four photosensitizers and two detergents were studied. Stern-Volmer plots were linear over the cell concentration range studied (0-10(7) cells/mL). The singlet-oxygen quenching constants obtained depended somewhat upon the specific combination of detergent and photosensitizer used. Extrapolation of the singlet-oxygen lifetime data to "100%" cell concentration (1.39 +/- 0.04 x 10(9) cells/mL) and correction for the contribution of the water solvent gave a singlet-oxygen lifetime between 0.17 and 0.32 microseconds for the L1210 leukemia cell. The theoretical contributions of various types of biological molecules within the L1210 cell to the total singlet-oxygen quenching were calculated from their concentrations and their quenching constants. These calculations suggest that proteins will quench most of the singlet-oxygen. Only about 7% of the singlet-oxygen is quenched by water.
authors.affiliation: Research Service, Edward Hines Jr. Department of Veterans Affairs Hospital, Hines, IL 60141.
authors.forename: A
authors.initials: A
authors.lastname: Baker
authors.forename: J R
authors.initials: JR
authors.lastname: Kanofsky
mesh_terms: D000818:Animals; D007700:Kinetics; D007939:Leukemia L1210 / Q000378:metabolism*; D049449:Luminescence; D051379:Mice; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism*; D010777:Photochemistry; D011838:Radiation-Sensitizing Agents; D026082:Singlet Oxygen; D013997:Time Factors; D014407:Tumor Cells, Cultured
chemical_list: D011838:Radiation-Sensitizing Agents; D026082:Singlet Oxygen; D010100:Oxygen