Isolation of three crystalline proteins from beef liver after partial purification by acetone fractionation

The isolation of three proteins in crystalline form from ground beef liver is described. These proteins are FTBL protein (Arch. Biochem. Biophys. 188, 251-265 (1978), crotonase, and catalase. Crotonase is isolated by crystallization from a 32% acetone extract of the ground liver. FTBL protein and catalase can subsequently be isolated from the same extract. For optimal yield and ease of isolation, FTBL protein is isolated from a 46.5% acetone extract from which catalase can subsequently be crystallized by dialysis. The isolation of FTBL protein as well as the isolation of catalase involves a preliminary fractional precipitation and solution before crystallization can be achieved. Isopropanol can be substituted for acetone in the isolation of the above three proteins and in the case of catalase, results in an exceptionally high yield. Methods for the recrystallization of the proteins are presented and the role of organic solvents in recrystallization is discussed.