Fractionation of nonhistone chromosomal proteins isolated from rabbit liver and submandibular salivary glands

Abstract Nonhistone chromosomal proteins were isolated from rabbit liver chromatin in 5 m urea, and in 5 m urea with stepwise increase in NaCl molarity. Five different fractions were obtained, including 5 m urea-extracted chromatin, 5 m urea-0.5 m NaCl, 5 m urea-0.5-1.0 m NaCl, 5 m urea-1.0–1.5 m NaCl, and 5 m urea-1.5–2.0 m NaCl. A total of 94 bands of different electrophoretic mobilities were found for nonhistone chromosomal proteins isolated from rabbit liver. In addition, studies on the melting profiles of the DNA pellets obtained from the variously treated chromatin indicated that DNA of ϱ = 1.688 g/cm 3 may have tightly bound nonhistones associated to it (i.e., nonhistones which are dissociated between 1.5 and 2.0 m NaCl in 5 m urea). This fraction contained specific nonhistones relative to the other fractions which were obtained at the lower NaCl molarity and which lacked histones (except for histone III).