A Method for the Determination of Adenosine- 5’-phosphoric Acid and Its Homologues*

For the determination of adenosine-5’-phosphoric acid and its homologues the methods which have been recommended chiefly are (1) enzymatic deamination by deaminase and quantitative determination of the ammonia split off (1) ; (2) determination on the basis of the pharmacological activity, (a) contraction of the isolated guinea pig uterus, (b) the characteristic change in the electrocardiogram upon intravenous injection into the rabbit (2) ; (3) isolation of the adenine by acid hydrolysis and nephelometric determination of its silver salt by comparison with standard solutions (3). Each of these methods may have its advantages for the investigation of special problems. There exist, however, cases in which none of them yields satisfactory results, particularly if a high specificity is required and if only small amounts of adenylic acid are available. By methods (2) and (3) differentiation between adenosine-5’-phosphoric acid and adenosine-3’-phosphoric acid’ is impossible; whereas, by method (1) adenosine as well as adenosine-5’-phosphoric acid is determined. Furthermore, in the latter method relatively large amounts are required, since the adenylic acid is the substrate of the enzymatic reaction. Despite the fact that the coenzyme properties of adenosine-5’-phosphoric