Sequential grouping of nonhistone chromosomal protein from pig thymus.

1. To establish a practical method to prepare nonhistone chromosomal proteins (NHP's) in substantial quantity, a sequential group fractionation procedure for NHP's from pig thymus chromatin has been developed by a combination of methods based on the intrinsic properties, such as binding force in chromatin, molecular weight, and acidity and/or basicity of the protein components. 2. The loosely bound NHP's in chromatin have been grouped into 11 subfractions, and tightly bound ones into 6 subfractions, 2 of which were histones. The loosely bound NHP's were chiefly acidic to neutral in contrast with the tightly bound components, which were basic. In addition, the NHP's of high molecular weight were in general acidic to neutral, while the lower molecular weight components were mainly basic. 3. The present method is applicable to the preparation of representative fractions of NHP on the scale of 50--400 mg from 1 kg of pig thymus.