SINGLET-OXYGEN GENERATION AT GAS-LIQUID INTERFACES: A SIGNIFICANT ARTIFACT IN THE MEASUREMENT OF SINGLET-OXYGEN YIELDS FROM OZONE-BIOMOLECULE REACTIONS |
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| Authors: | Jeffrey R. Kanofsky Paul D. Sima |
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| Affiliation: | Medical, Edward Hines, Jr., Department of Veterans Affairs Hospital, Hines, IL 60141 and Departments of Medicine and Biochemistry, Loyola University Stritch School of Medicine, Maywood, IL 60153, USA;Research Services, Edward Hines, Jr., Department of Veterans Affairs Hospital, Hines, IL 60141 |
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| Abstract: | Abstract— Several ozone-biomolecule reactions have previously been shown to generate singlet oxygen in high yields. For some of these orone-biomolecule reactions, we now show that the apparent singlet-oxygen yields determined from measurements of 1270 nm chemiluminescence were artifactually elevated by production of gas-phase singlet oxygen. The gas-phase singlet oxygen results from the reaction of gas-phase ozone with biomolecules near the surface of the solution. Through the use of a flow system that excludes air from the reaction chamber, accurate singlet-oxygen yields can be obtained. The revised singlet-oxygen yields (mol 1O2 per mol O3) for the reactions of ozone with cysteine, reduced glutathione, NADH, NADPH, human albumin, methionine, uric acid and oxidized glutathione are 0.23 ± 0.02, 0.26 ± 0.02, 0.48 ± 0.04, 0.41 ± 0.01, 0.53 ± 0.06, 1.11 ± 0.04, 0.73 ± 0.05 and 0.75 ± 0.01, respectively. These revised singlet-oxygen yields are still substantial. |
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