Phosphorus biological role

The biological roles of phosphorus include (1) anabolic and catabolic reactions, as exemplified by its essentiality in high-energy bond formation, e.g., ATP (adenosine triphosphate), ADP (adenosine diphosphate), etc., and the formation of phosphorylated intermediates in carbohydrate metabolism ... 

The elements of groups 13—16 fall into three categories (Fig. 1.3), the metalloids, the other metals, and the nonmetals. The important biological role of some of the nonmetals, oxygen, nitrogen, phosphorus, sulfur, and selenium together with the halogens, chlorine and iodine, will be discussed in Chapter 18. 

The use of QM-MD as opposed to QM-MM minimization techniques is computationally intensive and thus precluded the use of an ab initio or density functional method for the quantum region. This study was performed with an AMi Hamiltonian, and the first step of the dephosphorylation reaction was studied (see Fig. 4). Because of the important role that phosphorus has in biological systems [62], phosphatase reactions have been studied extensively [63]. From experimental data it is believed that Cys-i2 and Asp-i29 residues are involved in the first step of the dephosphorylation reaction of BPTP [64,65]. Alaliambra et al. [30] included the side chains of the phosphorylated tyrosine, Cys-i2, and Asp-i 29 in the quantum region, with link atoms used at the quantum/classical boundaries. In this study the protein was not truncated and was surrounded with a 24 A radius sphere of water molecules. Stochastic boundary methods were applied [66]. 

The following sections summarize only the most prominent interactions between the elemental cycles and the links in the hydrologic cycle. Water also plays a role in many chemical and biological reactions that are beyond the scope of this discussion. The carbon, nitrogen, sulfur, and phosphorus cycles are discussed in detail in Chapters 11, 12, 13, and 14, respectively. 

W. C. Plaxton, Metabolic aspects of phosphate starvation in plants. Phosphorus in Plant Biology Regulatory Roles in Molecular, Cellular, Organi.smic, and Eco.sy.s-lein Proces.ses (J. P. Lynch and J. Deikman eds.), American Society of Plant Physiologists, 1998, p. 229. 

Phosphorus is one of the inorganic macronutrients in all known forms of life. Inorganic phosphorus in the form of phosphate (PO/ ) plays a major role in vital biological molecules, such as DNA and RNA. Living cells also utilize phosphate to transport cellular energy via adenosine triphosphate (ATP). Phospholipids are the main structural components of all cellular membranes. Calcium phosphate salts are... 

Vitamin D3 is transported to liver where it undergoes a hydroxylation at C-25 into 1a,25-dihydroxyvitamin D3 (calcitriol) (Fig. 64). In the kidney, it undergoes further hydroxylations at different sites, depending on the serum Ca + concentration. The most biologically active metabolite of vitamin D3 is calcitriol, which plays important roles in the regulation of calcium and phosphorus metabolism. It is used for treating bone diseases, but is also involved in the cell proliferation and the inducement of cell differentiation [151]. 

Phosphorus (3IP, 7= 1/2) represents another element sensitive to NMR and consists of only one natural isotope. It has been studied since the beginning of NMR because it is an important element in the composition of inorganic compounds and has a very important role in biology. 

Phosphoryl and nucleotidyl transfer enzymes are extremely important and widespread in biology. They have in common the catalysis of nucleophilic reactions of phosphorus esters, and the general requirement for divalent metal ions, particularly Mg11, for activity. This requirement has stimulated considerable interest in the catalytic roles of divalent metal ions in these reactions. 

Vitamin D, along with parathyroid hormone and calcitonin, plays a primary role in calcium and phosphorus homeostasis in the body. Intensive research efforts over the past several years have elucidated a role for vitamin D in many other physiological processes as well. The biological actions of this seco-steroid are mediated primarily through the action of its polar metabolite, 1,25-dihydroxy vitamin D3 (l,25(OH)2D3). There is emerging evidence that l,25(OH)2D3 has many more target tissues than those involved in its classical role in the control of mineral metabolism. In addition, some of the actions of l,25(OH)2D3 may be mediated by mechanisms other than the classical steroid-receptor interaction. In this chapter we will provide a brief overview of the multiple actions of vitamin D3 and the pleiotropic mechanisms by which these actions are accomplished. 

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