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The Self‐Recognition and Self‐Assembly of Folic Acid Salts in Isotropic Water Solution
Author(s) -
Gottarelli Giovanni,
Mezzina Elisabetta,
Spada Gian Piero,
Carsughi Flavio,
Nicola Giovanni Di,
Mariani Paolo,
Sabatucci Annalaura,
Bonazzi Stefania
Publication year - 1996
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19960790123
Subject(s) - tetramer , chemistry , circular dichroism , crystallography , small angle x ray scattering , stereochemistry , scattering , organic chemistry , enzyme , physics , optics
The self‐assembly of alkaline folates in isotropic water solutions, with or without added salts, has been investigated by small‐angle neutron‐scattering, circular‐dichroism, and NMR techniques. The assembled species are chiral, cylindrical aggregates of finite length, composed of stacked tetramers; each tetramer is formed by Hoogsteen ‐bonded folate residues. The assembly process is more efficient in the presence of an excess of Na I ions, leading to longer aggregates with stronger tetramer‐tetramer‐tetramer interaction. In pure water, the rods are shorter and the tetramer‐tetramer interaction weaker. Association between folates can be detected by circular‐dichroism spectroscopy starting from a concentration of 6· 10 −4 mol l −1 , well below the critical concentration for the formation of the cholesteric mesophase ( ca. 0.5 mol l −1 ).