Dioxygen biology

Metal ions play an important role in several of these oxidative reactions as well as in biological dioxygen metabolism. As an example, copper(II) acetate and hydrogen peroxide have been used to produce a stable oxidizing agent, hydroperoxy copper(II) compound. The same oxidation system is also obtained from copper(II) nitrate and hydrogen peroxide (Eq. 1) [103] but requires the neutralization of ensuing nitric acid by potassium bicarbonate to maintain a pH 5. 

Modeling the active site features and the mechanistic key steps occurring in biological dioxygen activation is one of the most... 

Lipoxygenation is the major pathway of dioxygenation of arachidonic acid in blood platelets and leads to the 12-5-hydroperoxy acid 12-HPETE and the corresponding 12-hydroxy acid 12-HETE. Several pathways for the synthesis of 12-HETE have been developed. However, despite the availability of this substance, its biological role remains undetermined. 

A full discussion of the reactions of molecular oxygen involved in dioxygen adducts would require a separate review. Moreover, the reactions of co-ordinated molecular oxygen are discussed elsewhere l-8) dioxygen adducts of biological systems (7) and synthetic group VIII metal complexes 1,3) being of particular interest. 

It is also clear that copper is of little significance in most of these organisms relative to its multitude of roles in multicellular eukaryotes, while in these eukaryotes the role of nickel and cobalt is further diminished. We may conjecture that biological systems did not use copper extensively before the advent of an oxidizing atmosphere based on dioxygen (Frausto da Silva and Williams, 1991). 

At a macroscopic biological level, the damage to tissue is related to the concentration of photosensitizer and dioxygen in the tissues being irradiated, and to the light flux the key mechanistic questions here are—in which compartment does the photosensitizer accumulate,... 

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