Isolation of coenzyme A.

The coenzyme content was followed throughout the purification by the assay method described in a preceding paper (2). Hog liver was found most suitable. Ten 50 pound batches of liver were used in this preparation. Since rapid autolysis of Co A occurred, the yield was largely dependent on the rapidity with which the livers were obtained. Livers from still warm hog bodies were cut into small portions and added to an equal volume of boiling water. The temperature was not allowed to drop below 80”. After completion, the mixture was kept simmering for 15 minutes more. The juice was passed through muslin. Deproteinization and Mercury Precipitation-The juice was cooled and deproteinized with 5 per cent trichloroacetic acid. The filtrate was, as quickly as possible, neutralized to pH 5 and the coenzyme precipitated with a slight excess of mercuric acetate. The precipitate was collected after settling overnight, and decomposed with hydrogen sulfide. Acetone Fractionation and Barium Precipitation-The aerated filtrate from mercuric sulfide was neutralized to pH 4 to 5; 2 volumes of acetone were added, and the precipitate discarded. Another 7 volumes of acetone were added, and, after being kept overnight in the cold, the oily yellow deposit was collected by decantation. The oily deposit was dissolved in water, neutralized to pH 8.4 to 9, and barium acetate was added, followed by 2 volumes of acetone. The precipitate was dried with alcohol and ether. 50 pounds of liver gave 35 gm. of barium salt of 1.5 units per mg.