Adenosine 5 -phosphate, preparation

The reaction probably proceeds through the formation of an imino analogue of mixed anhydrides by nucleophilic displacement of cyanide during the phosphate activation. Cyanogen bromide was found to be more effective than DISN in this transformation. Since higher yields were obtained in the preparation of the cyclic phosphate from 3 -adenosinc phosphate than from 2/-adenosine phosphate, the authors suggested the formation of an activated... 

The evidence supporting this concept is derived from experiments on yeast extracts and pigeon liver preparations but further joint studies by Lipmann and Lynen make the formation of phosphoryl-ated or pyrophosphorylated coenzyme A improbable and suggest the formation of enzyme-bound adenosine phosphate and coenzyme A. In the presence of purified yeast enzymes isotopic pyrophosphate was found to exchange the isotope with ATP in the absence of coenzyme A. This excludes the latter as an obligatory participant. Isotopic acetate also exchanged readily with acetyl coenzyme A in the presence of this yeast enzyme. The following scheme of 3 reactions fits the facts ... 

Several cases have been documented in which a different, naturally occurring, glycosyl phosphate substitutes for the true substrate of the pyrophosphorylase. Adenosine 5 -(a-D-xylopyranosyl pyrophosphate) was prepared by the action of the pyrophosphorylase of adenosine 5 -(a-D-glucopyranosyl pyrophosphate) from wheat flour,218... 

Hydrolysis of sugar nucleotides with unspecific pyrophosphatases has already been mentioned (Section 11,1, p. 310). A similar reaction is catalyzed by a bacterial enzyme specific for adenosine 5 -(a-D-glucopyranosyl pyrophosphate).459 The specific conversion of uridine 5 -(a-D-glucopyranosyl pyrophosphate) into a-D-glucopyranosyl phosphate, uridine, and inorganic phosphate was observed with an enzyme from Escherichia colt 459,460 a preparation from Bacillus subtilis can act in a similar manner461 on different sugar nucleotides. ... 

Some of the reactions of PO3- parallel enzymatic reactions promoted by adenosine triphosphate (ATP). Pyruvate kinase catalyzes the equilibration of ATP and pyruvate with adenosine diphosphate (ADP) and phosphoenol pyruvate (11,12). In a formal sense, this reaction resembles the preparations of enol phosphate (eqs. 6 and 7). Cytidine triphosphate synthetase catalyzes the reaction of uridine triphosphate with ammonia to yield cytidine triphosphate (13). In a formal sense, this reaction resembles the replacement of the ester carbonyl group of ethyl acetate by the nitrogen of aniline (eq. 8). 

Figure 8.8 Retention times for adenosine (22.45 pmol), inosine (22.37 pmol), and hypoxan-thine (44.08 pmol) (A) standard prepared in mobile phase (B) standard prepared in incubation fluid or cell suspension medium. Conditions mobile phase, 125 mM potassium dihydrogen phosphate, 1.5% (v/v) acetonitrile, 20 mM triethylamine, and 1.0 mM tetrabutylammonium hydrogen sulfate (TBAHS) (pH 6.5) flow rate, 0.5 ml/min. (Reprinted from Ref. 18 with permission.)...

Histidine can be prepared from imidazole as in Scheme 117. It is a basic amino acid, the biosynthesis of which appears to involve adenosine 5 -phosphate, ribose phosphate and glutamine (which supplies a nitrogen for the imidazole ring) (Scheme 118). Histidine is one of the most important amino acids and has involvement in such biological processes as ester hydrolysis, acylation and (by virtue of its complexing power with iron) oxygen... 

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