Phosphorus

• Phosphorus is found in the human body only in combination with oxygen as phosphate. Most of the phosphate (as calcium phosphate) is stored in the skeleton. Bone is connective tissue, which is composed of calcified extracellular matrix and bone cells. The organic portion is composed of collagen fibers (type I collagen) and ground substance (keratine sulfate, chondroitin sulfate, hyaluronic acid). The inorganic moiety accounts for about 65% of the dry weight of bone. Type I collagen fibers are embedded in a complex of calcium phosphate as hydroxyapatite [Ca₁₀PO₄)₆(OH)₂].
• The phosphate group is also found in the composition of nucleic acids, proteins, phospholipids (in the cell membranes and blood lipoproteins), high energy compounds such as ATP and creatine phosphate.
• The phosphate group takes part in phosphorylation reactions catalyzed by the enzymes called kinases in many metabolic pathways as well as in the signal transduction pathway.
• Interactions: High phosphate intakes may impair the absorption of iron, copper and zinc. Thhe overuse of aluminium-containing antiacids may cause phosphate deficiency.