Premium
ψ Compaction of poly[d(AT)] · poly[d(AT)]
Author(s) -
Shin Yong A.,
Feroli Susan L.,
Eichhorn Gunther L.
Publication year - 1986
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.360251108
Subject(s) - chemistry , ionic strength , phase diagram , polymer , enantiomer , chirality (physics) , compaction , molecule , stereochemistry , crystallography , phase (matter) , organic chemistry , physics , materials science , nambu–jona lasinio model , chiral symmetry breaking , quantum mechanics , quark , aqueous solution , composite material
The compaction of poly[d(A–T)] · poly[d(A–T)] by Co(III) is accompanied by the formation of ψ(+)‐ and ψ(‐)‐structures. The chirality of the ψ‐structure depends on the Co(III) concentration, ionic strength, temperature, pH, and the chain length of the polymer. The two forms can be readily interconverted by manipulating these factors. Phase diagrams have been constructed that demonstrate the regions of stability of the enantiomers as a function of two variables, while other factors are held constant. At critical points in the phase diagram the two forms are in such unstable equilibrium that mechanical motion will cause ψ(+) ⇆ ψ(‐) interconversion. The formation of both ψ(+)‐ and ψ(‐)‐structures by the action of Co(III) on poly[d(A–T)] · poly[d(A–T)] contrasts markedly with the behavior of poly[d(G–C)] · poly[d(G–C)] in similar circumstances by forming only the ψ(+)‐structure and that of native DNA to produce no ψ at all. Thus the base sequence is important in determining the structure of chirally associated DNA molecules.