Hydration of ds-DNA and ss-DNA by neutron quasielastic scattering

• Type: Article in International Scientific Journal
• Date: 2004

Authors

Bastos, M (Author) FCUP; Castro, V (Author) Other; Mrevlishvili, G (Author) Other; Teixeira, J (Author) Other

Journal

Title: Biophysical Journal

Vol. 86 No. 2

Pages: 3822-3827

ISSN: 0006-3495

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 44 Citations

Scopus - 44 Citations

Scientific classification

FOS: Natural sciences > Biological sciences

Other information

Authenticus ID: P-000-A1A

DOI: 10.1529/biophysj.104.039586

Abstract (EN): Quasielastic neutron scattering measurements were performed in hydrated samples of ds-DNA and ss-DNA. The samples were hydrated in a high relative humidity atmosphere, and their final water content was 0.559 g H2O/g ds-DNA and 0.434 g H2O/g ss-DNA. The measurements were performed at 8 and 5.2 Angstrom for the ds-DNA sample, and at 5.2 Angstrom for the ss-DNA sample. The temperature was in both cases 298 K. Analysis of the obtained data indicates that in the ds-DNA sample we can distinguish two types of protons-those belonging to water molecules strongly attached to the ds-DNA surface and another fraction belonging to water that diffuses isotropically in a sphere of radius 2.8 Angstrom, with a local diffusion coefficient of 2.2 x 10(-5) cm(2) s(-1). For ss-DNA, on the other hand, no indication was found of motionally restricted or confined water. Further, the fraction of protons strongly attached to the ds-DNA surface corresponds to 0.16 g H2O/g ds-DNA, which equals the amount of water that is released by ds-DNA upon thermal denaturation, as studied by one of us (G.M.) by differential scanning calorimetry. This value also equals the difference between the critical hydration values of ds-DNA and ss-DNA, also determined by DSC. These results represent, thus, a completely independent measurement of water characteristics and behavior in ds- and ss-DNA at critical hydration values, and therefore substantiate the previous suggestions/conclusions of the results obtained by calorimetry.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 6