The isolation of globulins from cellular nuclei.

Behrens in 1932 (1) developed a method for isolating cellular nuclei. Lyophilized tissue was finely ground and the nuclei were isolated from other cellular debris by repeated centrifugation in organic solvents of suitable densities. The greater density of the nuclei makes this procedure possible. The method has been employed by various workers (2-5). Dounce et al. (4) reported that approximately one-half of the mass of these nuclei was removed by extraction with water adjusted to pH 6.0 with very dilute citric acid. 0.9 per cent sodium chloride solution also extracted much material from the nucleus, indicating that proteins other than nucleohistone and lipoprotein are present in appreciable quantities in nuclei. Nucleoprotein and lipoprotein (6) are predominantly present in nuclei isolated in aqueous media. Results of other investigations (7, 8) suggest that relatively large quantities of protein may be lost from nuclei isolated in aqueous media. The present paper reports an investigation of the nature of the proteins soluble in dilute salt solutions, proteins which are extractable from nuclei prepared by the Behrens method.