TY - JOUR
T1 - Impact of urea on water structure
T2 - A clue to its properties as a denaturant?
AU - Soper, A. K.
AU - Castner, E. W.
AU - Luzar, Alenka
N1 - Funding Information:
E.W.C. gratefully acknowledges support from the Donors of the Petroleum Research Fund. A.L. is pleased to acknowledge support from the National Science Foundation (CHE-9806058 and CHE-0211626) and the use of the UCSF Computer Graphics Lab (T. Ferrin, director, NIH RR-1081). We thank the editors of this special issue in honour of Walter Kauzmann the opportunity to report this work.
PY - 2003/9/1
Y1 - 2003/9/1
N2 - A new investigation of the structure of urea-water solutions at a mole ratio of 1 urea to 4 water molecules is described. Neutron diffraction is used in conjunction with isotope labelling on the water and urea hydrogen atoms and on the nitrogen atom of urea. The diffraction data are analysed using the empirical potential structure refinement procedure to yield a set of site-site radial distribution functions and spatial density functions that are consistent with the diffraction data. The results are discussed in relation to recent and past X-ray and neutron diffraction experiments and theoretical studies of this system. It is found that urea incorporates readily into water, forming pronounced hydrogen bonds with water at both the amine and carbonyl headgroups. In addition the urea also hydrogen bonds to itself, forming chains or clusters consisting of up to approximately 60 urea molecules in a cluster. There, is however, little or no evidence of urea segregating itself from water, in marked contrast to a recent study of the methanol-water system. This behaviour is discussed in the context of the great propensity of urea to effect protein denaturation.
AB - A new investigation of the structure of urea-water solutions at a mole ratio of 1 urea to 4 water molecules is described. Neutron diffraction is used in conjunction with isotope labelling on the water and urea hydrogen atoms and on the nitrogen atom of urea. The diffraction data are analysed using the empirical potential structure refinement procedure to yield a set of site-site radial distribution functions and spatial density functions that are consistent with the diffraction data. The results are discussed in relation to recent and past X-ray and neutron diffraction experiments and theoretical studies of this system. It is found that urea incorporates readily into water, forming pronounced hydrogen bonds with water at both the amine and carbonyl headgroups. In addition the urea also hydrogen bonds to itself, forming chains or clusters consisting of up to approximately 60 urea molecules in a cluster. There, is however, little or no evidence of urea segregating itself from water, in marked contrast to a recent study of the methanol-water system. This behaviour is discussed in the context of the great propensity of urea to effect protein denaturation.
KW - Hydration
KW - Isotope substitution
KW - Neutron diffraction
KW - Protein denaturation
UR - http://www.scopus.com/inward/record.url?scp=0141560450&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0141560450&partnerID=8YFLogxK
U2 - 10.1016/S0301-4622(03)00095-4
DO - 10.1016/S0301-4622(03)00095-4
M3 - Article
C2 - 14499925
AN - SCOPUS:0141560450
VL - 105
SP - 649
EP - 666
JO - Biophysical Chemistry
JF - Biophysical Chemistry
SN - 0301-4622
IS - 2-3
ER -