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Self‐assembly of dideoxyguanosine (3′,3′) and (5′,5′)‐monophosphates
Author(s) -
Proni Gloria,
Spada Gian Piero,
Gottarelli Giovanni,
Ciuchi Federica,
Mariani Paolo
Publication year - 1998
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/(sici)1520-636x(1998)10:8<734::aid-chir3>3.0.co;2-n
Subject(s) - chemistry , antiparallel (mathematics) , crystallography , chirality (physics) , phase (matter) , columnar phase , circular dichroism , polarity (international relations) , lyotropic , stereochemistry , liquid crystalline , chiral symmetry , biochemistry , physics , organic chemistry , quantum mechanics , magnetic field , nambu–jona lasinio model , cell , quark
The title compounds show a pronounced cation‐directed ability to self‐assemble in water and to gives columnar structures similar to four‐stranded helices; for compound (5′→5′)‐d(GpG), this leads to the formation of cholesteric and hexagonal liquid crystalline phases. Both phases are columnar and the cholesteric phase is left‐handed. This behaviour is a further confirmation of the tendency of guanine derivatives to self‐assemble to give stacked columnar structures whenever not impossible for structural reasons. The CD spectra of the aggregates in isotropic solutions are dominated by a negative exciton couplet centred around 250 nm associated to a left‐handed columnar chirality. The shapes of the profiles, in the 220–300‐nm region, for (5′→5′)‐d(GpG) (in water or in saline solutions) and for (3′→3′)‐d(GpG) (in KCl solution) are quasi‐mirror images of those of poly(G) and (3′→5′)‐d(GpG). The appearance of relatively intense CD signals around 280–300 nm in solution of (3′→3′)‐d(GpG) in the presence of NaCl resembles that of (3′→5′)‐d(GpG) in the presence of Rb + or Na + . In the compounds investigated in this work, which present two equivalent ends, one observes the two CD features that have been associated, in the current literature, with the signature of four‐stranded parallel and antiparallel structures: hence the origin of these CD bands cannot be found in the polarity of the strands. Self‐assembly is favoured by the addition of extra salt and the stabilising effect of K + is greater than that of Na + , in the case of (3′→3′)‐d(GpG), an assembled species could be detected by CD only in the presence of extra salt. Chirality 10:734–741, 1998. © 1998 Wiley‐Liss, Inc.