Nucleotide Phosphate ester hydrolysis

Cambella and Antia [385] determined phosphonates in seawater by fractionation of the total phosphorus. The seawater sample was divided into two aliquots. The first was analysed for total phosphorus by the nitrate oxidation method capable of breaking down phosphonates, phosphate esters, nucleotides, and polyphosphates. The second aliquot was added to a suspension of bacterial (Escherichia coli) alkaline phosphatase enzyme, incubated for 2h at 37 °C and subjected to hot acid hydrolysis for 1 h. The resultant hot acid-enzyme sample was assayed for molybdate reactive phosphate which was estimated as the sum of enzyme hydrolysable phosphate and acid hydrolysable... 

The nucleotide cyclic AMP (3, 5 -cyclic adenosine monophosphate, cAMP) is a cyclic phosphate ester of particular biochemical significance. It is formed from the triester ATP by the action of the enzyme adenylate cyclase, via nucleophilic attack of the ribose 3 -hydroxyl onto the nearest P=0 group, displacing diphosphate as leaving group. It is subsequently inactivated by hydrolysis to 5 -AMP through the action of a phosphodiesterase enzyme. 

Nucleosides and nucleotides are combinations of a base with a sugar. A nucleoside is an N-glycoside formed between a base and a sugar (usually ribose or deoxyribose). A nucleotide is a phosphate ester of a nucleoside. DNA nucleotides are more stable to acid hydrolysis of the glycosidic bond, which is one reason tfrat DNA has superceded RNA as the main genetic storage molecule it is less prone to mutation. 

In 1970, Eckstein and co-workers reported the first stereochemical study of an enzyme-catalyzed hydrolysis of a phosphate ester, the hydrolysis of the endo isomer of uridine 2, 3 -cyclic phosphorothioate (enrfo-cyclic UMPS) (72) by ribonuclease A (RNase A) 13). The hydrolysis of RNA catalyzed either by base or by RNase A proceeds by a two-step mechanism in which the 2 -hydroxyl group of a nucleotide unit within an RNA molecule acts as a nucleophile on the 3 -phosphodiester bond to displace the 5 -hydroxyl group of the neighboring nucleoside to form a 2, 3 -cyciic phosphate intermediate. RNase A then catalyzes the hydrolysis of this cyclic phosphate, mimicked by Eckstein s endo-cyclic UMPS, to yield the ultimate 3 -mononucleotide product. 

The first application of this 0 effect for determining the configuration of an oxygen chiral phosphate ester was the author s determination of the configuration of diastereomeric samples of cyclic [, 0]dAMP, the chiral substrate for studying the stereochemical consequences of the reverse reaction catalyzed by adenylate cyclase (formation of cyclic AMP from ATP), and of the hydrolysis reaction catalyzed by 3, 5 -cyclic nucleotide phosphodiesterase (25) (see Fig. 

Our work evolved from early investigations into the mechanism of hydrolysis of acyl chlorides (9-11) and the reactivity of nucleophiles toward organophosphorus compounds (12). I was intrigued at that time by the fact that some nucleophiles rapidly dealkylated phosphate esters and hence were important in deprotection in nucleotide chemistry, and other nucleophiles were rapidly phosphorylated, and this finding is important in the search for antidotes for the nerve gases and also in predicting the reactivity of organophosphorus insecticides. 

The low RBC ATP concentration is the most probable explanation for the hemolysis (1). In vitro studies of adenosine metabolism by intact patient s RBC showed as expected, a markedly decreased ATP synthesis from adenosine moreover, metabolic studies of adenylic nucleotides labelled with radioactive adenine indicate that AMP degradation (probably by hydrolysis of the phosphate ester followed by deamination of adenosine) is abnormally elevated in the patient s erythrocytes. Thus, the low RBC ATP concentration appears to be secondary to both a diminished synthesis of AMP from adenosine and an excessive catabolism of AMP. 

Besides the many esters isolated from yeast and muscle tissue, Levene and his associates prepared ribose 3- and 5-phosphates by hydrolysis of nucleotides (Wl). a-n-Glucose 1-phosphate was isolated by Cori, Colowick, and Cori ( 02) as a product of the phosphorolysis of glycogen. Leloir and... 

A method has been developed which is designed to remove nucleotide residues singly from a polynucleotide chain, and it is anticipated that more precise information will shortly be forthcoming regarding the order in which the nucleotides are linked.220 The method is based on the fact that esters of 3-oxo alcohols are unstable toward alkali. In agreement with this, it is found that the products of the action of periodate on adenosine 5-phosphate (XXX) or adenosine 5-(benzyl hydrogen phosphate) are hydrolyzed under very mild conditions. Thus, after removal of terminal, singly-esterified phosphoryl residues from a polynucleotide chain, it is anticipated that periodate oxidation and hydrolysis will result in the removal of the... 

Enzymes which catalyze the hydrolysis of the unit linkage of sequential residues of oligomers or polymers determine their substrate specificity by recognizing the particular unit residue in the sequential chain as well as the direction of the chain. For example, ribonuclease cleaves the 3 -phosphate of a pyrimidine nucleotide residue but not the 5 -phosphate, and trypsin hydrolyzes peptide bonds which involve the arginine or lysine residue at the carbonyl end but not at the amino end. This is also the case for the hydrolysis of a variety of synthetic substrates and quasi-substrates (Sect. 4.1). Synthetic trypsin substrates are ester or amide derivatives in which the site-specific group (positive charge) is contained in their carbonyl portion. 

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