Adenosine triphosphate formation

Vision loss may occur in deficiency states (thiamine or vitamin B12) or as a toxic response to certain drugs or substances (Box 22-5). In most cases one can establish that the patient has been exposed to toxins or has had some dietary deficiency. The precise pathogenesis of the atrophic process is somewhat obscure, although adenosine triphosphate formation appears to undergo a change. This change leads to a stasis of axoplasmic flow with subsequent optic disc edema, eventually resulting in axonal death. 

E Racker and W Stoeckenius (1974) Reconstitution of purple membrane vesicles catalyzing light-driven proton uptake and adenosine triphosphate formation. J Biol Chem 249 662-663... 

The two major metabolic pathways necessary for normal RBC metabolism are the hexose monophosphate shunt pathway, with its associated enzyme systems, and the Embden-Myerhof pathway of anaerobic glycolysis. The former is responsible primarily for maintaining Hgb in the rednced state and thns preventing the formation of methemoglobin, while the latter metabolizes glucose to lactic acid, which leads to adenosine triphosphate formation. 

ATP Adenosine triphosphate. Chemical energy generated by substrate oxidations is conserved by formation of high-energy compounds such as adenosine diphosphate (ADP) and adenosine triphosphate (ATP) or compounds containing the thioester bond. 

Several toxic compounds act by inhibiting the oxidation of carbohydrates or by inhibiting the formation of adenosine triphosphate (ATP), a molecule that... 

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). 

Nanninga, L.B. Mommaerts. C.R. (1960). Studies on the formation of an enzyme substrate complex between myosin and adenosine-triphosphate. Proc. Natl. Acad. Sci. USA 46, 1155-1166. 

F. H. Westheimer (1987) has provided a detailed survey of the multifarious ways in which phosphorus derivatives function in living systems (Table 4.7). The particular importance of phosphorus becomes clear when we remember that the daily turnover of adenosine triphosphate (ATP) in the metabolic processes of each human being amounts to several kilograms Phosphate residues bond two nucleotides or deoxynucleotides in the form of a diester, thus making possible the formation of RNA and DNA the phosphate always contains an ionic moiety, the negative charge of which stabilizes the diester towards hydrolysis and prevents transfer of these molecules across the lipid membrane. 

Another enzyme used for the measurement of glucose is hexokinase (EC 2.7.1.1) which catalyses the phosphorylation of glucose to produce glucose-6-phosphate with adenosine triphosphate as the phosphate donor and magnesium ions as an activator. The rate of formation of glucose-6-phosphate can be linked to the reduction of NADP by the enzyme glucose-6-phosphate dehydrogenase (EC 1.1.1.49). This indicator reaction can be monitored spectrophotometrically at 340 nm or fluorimetrically ... 

Kelly DP, Syrett PJ. 1964a. Inhibition of formation of adenosine triphosphate in... 

Acroldn concentration, 186,187 Adenosine triphosphate, effect of ozone on lung concentration of, 354 Aerosol carbon balance, 50 Aerosol formation, 4, 14, 674-76 ability index, 61 diemical medianisms of, 72 hydrox]4 radical-aromatic hydrocar> bon reaction, 76-81 ozone-olefin reaction, 72-76 condensable species vapor pressure and, 86-90,101... 

In the preceding sections the conversion of purines and purine nucleosides to purine nucleoside monophosphates has been discussed. The monophosphates of adenosine and guanosine must be converted to their di- and triphosphates for polymerization to RNA, for reduction to 2 -deoxyribonucleoside diphosphates, and for the many other reactions in which they take part. Adenosine triphosphate is produced by oxidative phosphorylation and by transfer of phosphate from 1,3-diphosphoglycerate and phosphopyruvate to adenosine diphosphate. A series of transphosphorylations distributes phosphate from adenosine triphosphate to all of the other nucleotides. Two classes of enzymes, termed nucleoside mono-phosphokinases and nucleoside diphosphokinases, catalyse the formation of the nucleoside di- and triphosphates by the transfer of the terminal phosphoryl group from adenosine triphosphate. Muscle adenylate kinase (myokinase)... 

The study of bioenergetics deals with energy formation and utilization in living systems. In most living cells energy is found in the form of adenosine triphosphate (ATP). Many biochemists believe that the cell is regulated, at least in... 

When vitamin BI2, reacts with adenosine triphosphate (ATP), alkylation lakes place as in Eq. 19.33 with the formation of a direct carbon-cobalt bond between adenosy and the metal, forming B,2 cocnzyme (Fig. 19.24). It acts in concert with several other enzymes to effect U-shifts of the general type ... 

Recently, the formation of a covalent glycosyl-enzyme intermediate was also shown by Bell and Koshland (17) in another reaction. Evidence was presented that the mechanism of the enzyme, phosphoribosyl-adeno-sine triphosphate pyrophosphate phosphoribosyl transferase, proceeds through a covalent phosphoribosyl-enzyme intermediate. The intermediate has been demonstrated after incubating the enzyme with 14C-5-phosphoribosyl-l-pyrophosphate (PRPP) under native and denaturing conditions. The intermediate also forms from the reverse direction as shown when the enzyme is mixed with its product N- (5-phosphoribosyl-adenosine triphosphate (PR-ATP). These data give evidence for a covalent enzyme-substrate intermediate. The enzyme which catalyzes the overall reaction proceeds as follows ... 

Fig 2 Formation of morphine glucumnide. NAD = nicotinamide adenine dmuiteotidn NADH = reduced NAD ATP — adenosine triphosphate ADP = adenosine diphosphaie HIP = uridine triphosphate LrDP = undine diphosphate... 

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