Copper, Biological Functions
To understand the biological functions of copper is first to realize that the advent of copper (and iron) into the biosphere was timed with an enrichment of O2 in the atmosphere. Consequently, many copper enzymes use O2 as a substrate and in so doing have endowed living systems with the means to cope with a potentially toxic gas.
In biological systems, copper is primarily a catalytic metal. The scarcity of copper in the system puts it in the category of a micronutrient, or more specifically a trace metal. Foremost in its actions is to allow the system to deal with iron. Other studies have linked copper in animals and humans with the synthesis of neurotransmitters, pituitary hormones, biopigments, and the establishment of a firm connective tissue network, functions that are manifested through copper-dependent enzymes. Copper in plants in confined mainly to the photosynthetic...