[Biological function of some elements and their compounds. I. Oxygen--the element of life and death].Pol Merkur Lekarski. 2009 Sep; 27(159):245-8.PM
Oxygen in cells occurs with carbon and hydrogen in most organic compounds that have either structural or metabolic functions. Atomic and molecular oxygen in singlet form or as free radicals (i.e., superoxide anionic radical, hydroxide radical) and as hydrogen peroxide, peroxidenitrate (III), nitrogen oxide are harmful to cellular structure and its metabolism and induce harmful genic mutations. Oxygen reactive species are secondary signaling molecules for transcription factors and cytokines. Therefore, it is crucial to maintain homeostasis at the level of reaction of oxidation and reduction. It is important for such significant biological processes as DNA synthesis, enzymes activation, cellular cycle regulation, gene transcription activation, and apoptosis. The review is also devoted for oxygen carriers in living organisms, e.g., hemoglobin, mioglobin and the toxicity of oxygen and ozone.