Concentration dependence of hydration water in a model peptide.
The molecular dynamics of aqueous solutions of a model amphiphilic peptide is studied as a function of concentration by broad-band light scattering experiments. Similarly to protein aqueous solutions, a considerable retardation, of about a factor 6-8, of hydration water dynamics with respect to bulk water is found, showing a slight dependence on solute concentration. Conversely, the average number of water molecules perturbed by the presence of peptide, i.e. the hydration number, appears to be strongly modified by adding solute. Its behaviour, decreasing upon increasing concentration, can be interpreted considering the random close-to-contact condition experienced by solute particles. Overall, the present findings support the view of a "long range" effect of peptides on the surrounding water, extending beyond the first two hydration shells.
IOM-CNR c/o Dipartimento di Fisica e Geologia, Università di Perugia, Via Pascoli, I-06123 Perugia, Italy. lucia.comez@fisica.unipg.it.
Lucia
L
Comez
Stefania
S
Perticaroli
Marco
M
Paolantoni
Paola
P
Sassi
Silvia
S
Corezzi
Assunta
A
Morresi
Daniele
D
Fioretto
D008956:Models, Chemical; D010455:Peptides / Q000737:chemistry*; D013059:Spectrum Analysis, Raman; D014867:Water / Q000737:chemistry*
D010455:Peptides; D014867:Water