Singlet-oxygen generation at gas-liquid interfaces: a significant artifact in the measurement of singlet-oxygen yields from ozone-biomolecule reactions.
Several ozone-biomolecule reactions have previously been shown to generate singlet oxygen in high yields. For some of these ozone-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 +/- 0.2, 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.
Kanofsky
J R
JR
Medical Service, Edward Hines, Jr., Department of Veterans Affairs Hospital, Hines, IL 60141.
Sima
P D
PD
D000418:Albumins / Q000737:chemistry; D003545:Cysteine / Q000737:chemistry; D005740:Gases; D005978:Glutathione / Q000737:chemistry; D006801:Humans; D008715:Methionine / Q000737:chemistry; D009243:NAD / Q000737:chemistry; D009249:NADP / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry*; D010126:Ozone / Q000737:chemistry*; D026082:Singlet Oxygen; D014527:Uric Acid / Q000737:chemistry
D000418:Albumins; D005740:Gases; D009243:NAD; D026082:Singlet Oxygen; D014527:Uric Acid; D009249:NADP; D010126:Ozone; D008715:Methionine; D005978:Glutathione; D003545:Cysteine; D010100:Oxygen