Pyridine, nucleotide triphosphate

Compounds that serve as energy carriers for the chemotrophs, linking catabolic and biosynthetic phases of metabolism, are adenosine phosphate and reduced pyridine nucleotides (such as nicotinamide dinucleotide or NAD). The structure of adenosine triphosphate (ATP) is shown in Fig. 1. It contains two energy-rich bonds, which upon hydrolysis, yield nearly eight kcal/mole for each bond broken. ATP is thus reduced to the diphosphate (ADP) or the monophosphate (AMP) form. 

Acid-soluble extracts can be assayed for certain nucleotides by enzymatic methods. Various assay procedures for the adenosine phosphates and the pyridine nucleotide coenzymes are available 22,33). Specific methods for the determination of picomole amounts of the four deoxyribonucleoside triphosphates have been reported recently 15,16). 

Aqueous 0.15M sodium chloride solution is convenient for fractionating mono-, di- and triphosphates on DEAE- and ECTEOLA-cellulose [59]. 0.3—0.5M lithium chloride may be used in TLC on PEI-cellulose of these compounds as well as of pyridine-nucleotides the separations do not take longer than 15 min [51, 63, 70, 75]. 0.3 0.8M ammonium sulphate is also suitable for fractionation of mono-, di- and triphosphates [77]. 

It was first observed that adrenal homogenates and crudely fractionated particles require or can be activated by various cofactors and combinations of cofactors and metabolic intermediates, such as glucose, fumarate and other citric acid cycle components, adenosine triphosphate (ATP) or adenylic acid, nicotinamide or diphospho-pyridine nucleotide (DPN) (334,386,570,721) or triphosphopyridine nucleotide (TPN) in place of DPN plus ATP (335,786). The activity of meticulously prepared adrenal mitochondria is inhibited by low concentrations of dinitrophenol it was therefore suggested that lljS-hydroxylation requires concurrent oxidative phosphorylation (112,386). 

The first examples of supercharged nucleotide analogues (85-87) have been described, in which methylenebisphosphonic acid containing an additional ioni-sable acidic function has been incorporated into p,y-bridged derivatives of adenosine triphosphate. The compounds and their protected precursors were obtained following acid-catalysed reaction of the respective precursors (88-90) with adenosine 5 -phosphoromorpholidate in pyridine in yields of 80,75 and 25%. 

Phosphorylation of adenosine (191) with an excess of dibenzyl phos-phorochloridate in pyridine gave three nucleotide products, the 2, 5-diphosphate (192) and the 3, 5 -diphosphate (193), and a small proportion of the 2, 3, 5 -triphosphate (194). As expected, (192) and (193) are interconvertible in acid solution. Phosphorylation of adenosine 2 3 -cyclic phosphate also affords the mixed diphosphates (192) and (193), without formation of any (194). 

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