Critical amount of oligovalent ion binding required for the B-Z transition of poly (dG-m5dC).

AUTOR(ES)

Chen, H H

RESUMO

By working at very low Na+ concentrations (1mM and less), the number of bound Mg(2+), cobalt hexamine (3+), and spermine (4+) necessary to induce the B-Z transition of poly (dG-m5dC) has been directly measured. The results show that if as little as 1 cobalt hexamine(3+) or spermine(4+) is bound per 40-50 nucleotides the transition will occur. A greater fraction of bound Mg(2+) is required, 1 bound Mg(2+)/10 nucleotides. The dependence of the transition midpoint concentrations of oligovalent ions on Na+ concentrations suggests that specific ion binding energies, not included in counterion condensation theory, are responsible for the transition.

Documentos Relacionados

• Length changes in solution accompanying the B-Z transition of poly (dG-m5dC) induced by Co(NH3)63+.
• Effect of the B--Z transition in poly(dG-m5dC) . poly(dG-m5dC) on nucleosome formation.
• Effects of methylation on a synthetic polynucleotide: the B--Z transition in poly(dG-m5dC).poly(dG-m5dC).
• Thermodynamics of the B to Z transition in poly(m5dG-dC).
• Thermodynamics of B-Z transition in supercoiled DNA.