Effects of some metal ions on the denaturational heat capacity increments in dilute solutions of ds-DNA

• Type: Article in International Scientific Journal
• Date: 2002

Authors

Mrevlishvili, GM (Author) Other; Sottomayor, MJ (Author) FCUP; da Silva, MAVR (Author) FCUP

Journal

Title: Thermochimica Acta

Vol. 394

Pages: 83-88

ISSN: 0040-6031

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 3 Citations

Scopus - 3 Citations

Scientific classification

FOS: Natural sciences > Chemical sciences

Other information

Authenticus ID: P-000-MNV

DOI: 10.1016/s0040-6031(02)00241-1

Abstract (EN): The native DNA duplex may be viewed as a cooperatively-ordered H bonded structure, including well localized Watson-Crick base pairs and H-bounded networks of hydration parts of the DNA-solvent interface in the grooves of the helix. In this paper, we present the effect of different metal ions (Li+, Mg2+ and Cu2+) on the denaturational heat capacity increment (DeltaC(p)) for calf thymus DNA. Since the contribution from the ordered hydration water fraction disruption energy to the total enthalpy and heat capacity increment values of double helix melting is significant, it must be possible to detect the effect of metal ions on the structural ordering/disordering of the H-bounded network in the hydration shell of the DNA duplex. Experimental results suggest that Li+, which is preferentially adsorbed in the minor groove of B-DNA and should contribute significantly to the stabilization of B-form, has a pronounced influence on the value of DeltaC(p). For the system Mg2+-DNA, the values of DeltaC(p) are also significant, which can be explained by the formation of inner hydration sphere complexes and immobilization of structural water by the grooves of the duplex, stabilizing the helix. The effect of Cu2+ ions is much more pronounced. The satellite peaks of calf thymus DNA become lower as the concentration of Cu2+ increases and for concentrations of Cu2+ higher than 0.010M, they disappear and DeltaC(p) = 0. This is indicative of the known preference of Cu2+ for purins and GC rich sites of DNA, binding to the N7 of guanine. As a result, disruption of the base stacking and hydrogen bounded water networks in the grooves of the double helix takes place.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 6