Adenosine diphosphate indications

Figure 17-2. The pathway of glycolysis. ( ,—P, HOPOj " .inhibition.) At asterisk Carbon atoms 1-3 of fructose bisphosphateform dihydroxyacetone phosphate, whereas carbons 4-6 form glyceraldehyde 3-phosphate. The term "bis-," as in bisphosphate, indicates that the phosphate groups are separated, whereas diphosphate, as in adenosine diphosphate, indicates that they are joined.

They release adenosine diphosphate [58-64-0 (ADP) and thromboxane [57576-52-0] which results in vascular contraction and, indirectiy, in the formation of fibrin clot. Platelet transfusions are indicated for patients with thrombocytopenia, ie, a shortage of healthy platelets or thrombocytopathy, ie, platelet malignancy associated with spontaneous hemorrhages. 

The structure and formation of ATP. (A) The chemical structure of adenosine triphosphate (ATP). "C" indicates carbon, "N" nitrogen, "O" oxygen, "H" hydrogen and "P" phosphorus. Note the negative charges on the phosphate groups (PO3 ). (B) ATP can be formed from adenosine diphosphate (ADP). 

The development of an acute retinal artery obstruction in a young, otherwise healthy man was associated with excessive use of an oxymetazoline nasal spray. Platelet coagulation studies indicated a platelet aggregation hypersensitivity to adenosine diphosphate and adrenaline. Predisposition to sympathomimetic drug-induced platelet fibrin embolus formation may have played a role in this case (2). 

Aune and Pogue344 presented data indicating that at least two distinct mechanisms, (1) stimulation of cellular catabolism of tryptophan and (2) stimulation of cellular catabolism of nicotinamide adenine dinucleotide (NAD) by adenosine diphosphate-ritosyl transferase (ADP-RT), can account for IFN-y-mediated inhibition of tumor cell growth. Both mechanisms appear to be sensitive to oxygen tension and to changes in intracellular glutathione concentrations, and both mechanisms lead to loss of intracellular NAD. 

Nicotinamide mononucleotide is not a cofactor for bovine GDH 31 la). However, replacement of the adenine moiety of the coenzymes with either hypoxanthine, cytidine, or nicotinamide yields a derivative which will function as eoenzyme, although with diminished efficiencies of 91, 53, and 3% (relative to the activity with NAD), respectively. Nicotinamide mononucleotide phosphoriboside is 0.4% as effective as NAD. These data, which give further indication of the lack of specificity in the adenosine diphosphate site, show that although the adenosine moiety of the coenzyme may be altered in a number of ways, it must be present in some form in order for the analog to function as a cofactor. 

In platelets from healthy persons and patients with coronary artery disease (CAD), the effect of an ethanol extract of arjuna on platelet function indices was determined by incubating the platelets with arjuna extract in a time- and dose-dependent (concentrations of 25 to 100 ng/ml) manner in the presence and absence of adenosine diphosphate (ADP). Arjuna was able to significantly inhibit platelet aggregation in platelets from CAD patients and from healthy controls. Significant attenuation of intracellular free calcium release and expression of CD62P was also observed after treatment with arjuna (Malik et al. 2009). 

The ADP in the above reaction indicates adenosine diphosphate, which has the same structure as ATP but which has one less terminal phosphate group. By an entirely different procedure, Strehler (34) has been able to show that the ATP content of illuminated Chlorella is markedly increased following an anaerobic period in the dark. There seems to be little doubt that the production of high-energy phosphate bonds is connected to the photochemical phase of photosynthesis, but the mechanism of the reactions involved is not well understood at the present time. 

Fig. 7.2 The complex structure of coenzyme A displays a phosporylated adenosine part. The diphosphate bridge connects to a substituted ethanolamine derivative that ends in a reactive SH-group. The broken and thick lines indicate the special stereochemical feature of Co A...

Fig. 13.17. Scattergram of the absolute value of r,4 versus the distance in adenosine and guanosine fragments (top data from small molecule structures, bottom data from protein structures). In the former case, the distribution clusters in the lower left quadrant of the parameter space. In the protein case, the ligands with a terminal diphosphate group (O) are found in the same range, whereas the dinucleotides (NAD, NADPH, FAD ) are mainly observed at large r,4- and rf3-val-ues. The small molecule structure of the Li-salt of NAD is indicated (O, left)...

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