Improved Method for Isolation of Adenosine Di-and Triphosphates The technique used by Albaum (I) for isolation of adenosine polyphosphates from higher plants has been applied in the present studies to conidia of Neuro-spora sitophila (Mont.) Shear and Dodge. In order to extract acid-soluble phosphates quantitatively from conidia, however, it was necessary to repeat the extraction five or six times with three volumes of 5-percent trichloroacetic acid (TCA). This resulted in a large volume of liquid and very dilute solutions of phosphates. Under these conditions, 50 percent or more of the orthophosphate and adenosine diphosphate present in the original TCA extracts was lost in the barium isolation procedure. No efficient means have been found for complete breakage of the conidia; therefore, the volume of TCA could not be diminished by homogenation, which is possible when many other source materials are used. A search was made, therefore, for a cation that would precipitate phosphates more nearly completely than barium in dilute solutions and that would still lend itself to convenient isolation and purifi-cation of adenosine triphosphate (ATP) and adenosine diphosphate (ADP) by adsorption on anionic exchange resin by the method of Cohn and Carter (2). Of the several cations tested, ZnI* was found to be most suitable. With zinc, the step involving dissolution ofthe original precipitate in HCl could be eliminated because the zinc phosphates are soluble in lN NH4OH, and zinc, in this solution, passes readily through the resin column, whereas orthophosphate, ATP and ADP ions are adsorbed.

For the purpose of comparing zinc and barium as precipitating agents, isolation of phosphates from one-half of TCA extracts, usually about 200 ml, was done with barium as described by Albaum (1), and from the other half with zinc as fol-lows. Five milliliters of 25-percent zinc acetate solution were added to the ex-tract. The solution was cooled to 0 C and the precipitate was collected by cen-trifugation. The precipitate was washed once with 15 ml of cold distilled water to remove excess TCA and then resedi-mented. It was dissolved in15 ml of IN NH, OH and passed several times through a 2-to 3-cm column of Dowex