Anion exchange chromatography of acids of the citric acid cycle.

The demonstration of the accumulation of citrate in vivo in the presence of fluoroacetate and the specific modification of this effect produced in various organs by the injection of malonate (14) have increased the desirability of isolation and quantitative determination of the acids of the Krebs cycle and related substances. Further, proposed studies involving the use of radioactive tracers require the isolation of these acids in pure form. Although partition chromatography by means of silica gel columns has been used with notable success for separation of some of these acids (5-8), difficulties in the separation of certain pairs of acids, such as lactic and succinic, and limitations on the quantities of acids resolvable, led us to the use of ion exchange chromatography (9). While ion exchange resins were used for separation of the acidic group of amino acids from the neutral and basic groups (10, ll), the use of these resins for chromatographic separation of individual amino acids was first reported by Stein and Moore. (12, 13). Recently, Cohn has described the separation of nucleotides and purine and pyrimidine bases by ion exchange columns (14). This study is-an extension of the use of these resins to the separation of acids of the Krebs cycle.