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多数生物的需氧浓度只要稍高于空气中含氧量就会有毒于生命。在某些情况,甚至普通空气中的氧对机体也有害。生理情况下,氧在体内代谢最后还原成水时,产生少量自由基,后者在酶和非酶物质的作用下不断被消灭。一般每克组织含自由基10~(-8)M,自由基增多可引起蛋白质分子结构疏散、核酸链断裂和多糖解聚;不饱和脂肪酸受过氧化作用形成过氧化脂质。以上过程造成膜系
The oxygen concentration of most organisms will be toxic to life as long as it is slightly higher than the oxygen content in the air. In some cases, even oxygen in the normal air is harmful to the body. Under physiological conditions, when oxygen is metabolized into water in vivo, a small amount of free radicals are produced, and the latter are continuously destroyed by the action of enzymes and non-enzymatic substances. Each gram of tissue contains 10~(-8) M free radicals. Increased free radicals can cause evacuation of protein molecules, cleavage of nucleic acid strands, and depolymerization of polysaccharides; unsaturated fatty acids are peroxidized to form lipid peroxides. The above process caused the film system