Nucleic Acids Research, 1987, Vol. 15, No. 16 6655-6684
© 1987
Articles |
Reversibility of the low-salt transition of chromatin core particles
Department of Biochemistry and Biophysics, Oregon State University Corvallis, OR 97331, USA
Received April 14, 1987. Revised July 16, 1987. Accepted July 16, 1987.
The low-salt transition of chromatin core particles is reversible if the monova-lent cation concentration is kept above 0.2 mM. Exposure of the particles to salt concentrations below this value results in a nonreversible secondary transition. The nonreversible changes are relatively slow with a half-time of about 15 minutes. Once exposed to such low ionic strength, the particles then begin to refold with increasing salt in at least two steps over a much higher ionic strength range than is required for the usual low-salt transition. The refolding is very fast, with a half-time less than a minute. Small differences between particles which had or had not been exposed to very low salt persist even when the particles are returned to near physiological ionic strengths.