Phosphorus release mechanisms

Mechanism of Action A bisphosphonate that inhibits the resorption of mineralized bone and cartilage inhibits increased osteoclastic activity and skeletal calcium release induced by stimulatory factors produced by tumors. Therapeutic Effect Increases urinary calcium and phosphorus excretion decreases serum calcium and phosphorus levels. 

However the mechanism of the antimicrobial effect of silver nanoparticles is not well understood. It has been recently reported that Nanosilver represents a special physicochemical system which confers its antimicrobial activities via Ag-t [11]. According to Morones et al., the bactericidal effect of silver nanoparticles on microorganisms is connected not merely with the release of silver ions in solution [12]. Silver nanoparticles can also be attached to the surface of the cell membrane and drastically distnrb its proper function [12]. They could also penetrate inside the bacteria and canse farther damage by interacting with sulfur and phosphorus-containing componnds snch as DNA. 

The parallelism in reactions with HMPT and mixtures of phosphorus pentoxide and amines can best be realized by looking at the mechanism of HMPT reactions [1 5 ]. In the reaction of p-methoxy-benzylalcohol with HMPT which produce the corresponding N,N-dimethylbenzyl amine--p-methoxybenzyl phosphate was identified in the XP NMR spectrum of the reaction mixture. Since pyrophosphate was also observed during the reaction of the benzyl alcohol with HMPT, the intermediate formation of the metaphosphate anion can be assumed. Addition of the benzyl alcohol to that anion then produce the benzyl phosphate. Phosphate ions are known to be good leaving groups so that a benzylamine can easily be produced from the phosphate by reaction with di-methylamine released from the dimethylammonium ion. The phosphoric acid produced during the reaction is believed to react with HMPT, so that more dihydro-gen-bis(dimethylammonium) pyrophosphate is formed. 

Vicinal syn- and aufi-diols, as shown in Figure 4.42, can be prepared diastereoselectively (cf. Figures 8.10,8.13-8.15,8.32). In the Corey-Winter process they are first converted into cyclic thiocarbonates (cf. Section 6.4.4 for a similar reaction mechanism). Upon heating in trimethyl phosphite, these thiocarbonates furnish olefins. In what is evidently a one-step reaction, phosphorus and sulfur combine with one another and the five-membered heterocycle fragments. C02 is released and the olefin results from a xyu-elimination. Because of the latter, a syu-diol gives the trans-oieim and an anti- diol gives the cw-olefin in the Corey-Winter sequence. 

FUNCTION Maintains the level of calcium in the blood, acting mainly on bone and kidney. In bone, PTH stimulates osteoclast cells to produce bone breakdown with release of calcium and phosphorus (PTH has a similar effect in this regard as vitamin D, but operates by a different mechanism PTH acts through cyclic AMP). In the kidney, PTH increases calcium reabsorption and phosphate excretion (vitamin D, however, increases absorption of both calcium and phosphorus in the kidney). 

Figure 18.28. ATP Synthesis Mechanism. One of the oxygen atoms of ADP attacks the phosphorus atom of Pj to form a pentacovalent intermediate, which then forms ATP and releases a molecule of H2O.

---