Nucleosome core histone complex isolated gently and rapidly in 2 M NaCl is octameric.

Abstract

A relatively stable specific complex of the chromatin core histones H2A, H2B, H3, and H4 has been obtained in 2 M -NaCl/25 mM sodium phosphate buffer, pH 7.0. The histone core complex has an apparent specific volume of 0.73 ml/g. Its sedimentation coefficient was dependent on rotor speed (angular velocity, w) and attained different stable values at low and high rotor speeds. The drop in sedimentation coefficient occurred sharply between w2 values of about 9 X 106 and 1

Octamer reconstitution from acid‐extracted chicken erythrocyte histones

“…No difference could be detected by determining the sedimentation velocities at 56~ rev./min. The sedimentation velocity at 16000 rev./min is in close agreement with that of 2.63 S reported [8] for rat Iiver octamer in 2 M NaCl, 25 mM phosphate (pH 7) and corresponds to an ~20,~ of 6.6 S 181. However, in [S], rat liver octamer broke down to a species with an ~20,~ of 3.8 S above 28000 rev,/min, compared with 3.8 S for a chicken octamer preparation centrifuged at 59000 rev./min in 2 M NaCl, 10 mM cyclohexylaminoethane sulfonic acid (pH 9) in 191.…”

Reconstitution of native-like nucleosome core particles from reversed-phase-HPLC-fractionated histones

“…Under the experimental conditions (see Figure 5A) native core histones sediment as a monodisperse sample, with 3.8p0.2 S, in agreement with previous reports [28][29][30][31]. In contrast, RP-HPLCpurified histones (fraction C, Figure 1) exhibit a significant extent of heterogeneity ( Figure 5A2), with only approx.…”

Histone octamer: dissociation in ultracentrifugal fields and subsequent reassociation into lower oligomers

“…At 40000 rev./min the core protein in 2 M NaCl at 4°C sedimented as one boundary [16] and the Van Holde plot of the sedimentation data ( fig. 2) was linear.…”

“…Histone Hl and the core protein were prepared as in [16,17]. Ultracentrifugal field relaxation experiments were done as in [ 181.…”

“…We showed in [16] that the core protein obtained gently and rapidly in 2 M NaCl at pH 7 is octamerit with an ~200,~ of 6.6 S, a Dzo,~ of 5.4 x lo-' cm'.s-l and Mr 108000 f 2500. This octameric complex undergoes a sharp conformational transition at centrifugal forces *60000 x g to a species with an sto ,w of 3.8 S, a value reported for the heterotypic tetramer [2].…”