Preparation of pure cytochromecfrom heart muscle and some of its properties

Theorell described recently (1935, 1936) a large-scale method of preparation of cytochrome c from ox heart. According to this method, minced muscle is defatted with acetone and benzol, dried, pounded, washed three times with water and extracted with decinormal sulphuric acid. The extract is neutralized, the precipitate centrifuged off, and the fluid considerably reduced in bulk by evaporation. The solution is then fractionated with ammonium sulphate giving finally cytochrome containing 0·17 % of iron which is about 50 % pure. Further purification was carried out by adsorption on barium sulphate and elution with decinormal HCl or by adsorption on cellophane, which is sectioned with a freezing microtome, and elution with dilute ammonia. The final steps of purification, according to Theorell, give samples of cytochrome containing 0·34 % of iron. The yield of this material, which Theorell rightly considers to be pure cytochrome, is approximately 1 g. per 100 kg. of heart muscle.