Expired pentane, an index of lipid peroxidation, and pulmonary function were measured as a function of exercise for 1 h with and without exposure to 0.3 ppm ozone. In experiment 1, 10 subjects who exercised on a bicycle ergometer at 50% of maximal oxygen consumption while being exposed to 0.3 ppm ozone had increased lung residual volume and decreased vital capacity, maximal midexpiratory flow rate, and forced expiratory volume in 1 s. In experiment 2, breath collected into a spirometer filled with hydrocarbon-scrubbed air showed increased pentane from the stress of exercise but no effect of ozone. During rest and exercise in experiment 3, two of six subjects had higher pentane levels than the other subjects. Following daily supplementation with 1,200 IU dl-alpha-tocopherol for 2 wk, the mean production of pentane during rest and exercise was significantly lowered, and there was no difference in pentane production among the subjects. It was concluded that lipid peroxidation occurs during exercise and that it is attenuated by vitamin E.
A procedure was developed to isolate 75Se-labeled rat liver glutathione peroxidase (glutathione:H2O2 oxidoreductase, EC 1.11.1.9) at 30--50% purity with 20--30% yields in 4--5 days. Using these preparations of glutathione peroxidase, the selenium moiety in the enzyme was identified as selenocysteine by derivatizing the seleno group with either iodoacetate or ethylenimine in the intact protein, hydrolyzing the protein with 6 N HCl, and cochromatographing the 75Se-labeled products with known standards. Techniques employed were anion-exchange chromatography, cation-exchange chromatography, gel-permeation chromatography, two-dimensional thin-layer chromatography, and automated amino acid analysis. The selenocysteine moiety was identified as the catalytic site in glutathione peroxidase by specifically labeling the enzyme with [14C]iodoacetate on the 75Se-labeled selenium atom and fractionating the 14C, 75Se-labeled derivative after acid hydrolysis. It was concluded that the reduced form of glutathione peroxidase contains the selenocysteine selenol (-SeH) at the catalytic site.
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