Temporal binding of urea to lysozyme was examined using X-ray diffraction of single crystals of urea/lysozyme complexes prepared by soaking native lysozyme crystals in solutions containing 9 M urea. Four different soak times of 2, 4, 7 and 10 hours were used. The five crystal structures (including the native lysozyme), refined to 1.6 Å resolution, reveal that as the soaking time increased, more...

Rheological forces in the blood trigger the unfolding of von Willebrand factor (VWF) and its A2 domain, exposing the scissile bond for proteolysis by ADAMTS13. Under quiescent conditions, the scissile bond is hidden by the folded structure due to the stabilisation provided by the structural specialisations of the VWF A2 domain, a vicinal disulphide bond, a calcium binding site and a N1574-glyca...

The intermolecular bonding between molecules containing urea moieties is of interest due to the possible bidentate nature of the hydrogen bond. Experimentally, the nature of the hydrogen bond can be determined from the infra-red spectrum of thematerial. TheC=Ostretching frequency shows substantial shifts due to the additional constraints of the hydrogen bonding. To ascertain the capability of q...

A new class of efficient hydrogelators has been developed by a simple modification of the peripheral substituents of cyclohexane bis-urea organogelators with hydrophilic hydroxy or amino functionalities. These bis-urea hydrogelators were synthesised in two or three steps using an alternative procedure to the common isocyanate method. Gelation was obtained with organic solvents, water and strong...

The amphiphilic osmolyte trimethylamine-N-oxide (TMAO) is commonly found in natural organisms, where it counteracts biochemical stress associated with urea in aqueous environments. Despite the important role of TMAO as osmoprotectant, the mechanism behind TMAO's action has remained elusive. Here, we study the interaction between urea, TMAO, and water in solution using broadband (100 MHz-1.6 THz...

5-Fluoro-2'-deoxyuridylate causes a rapid inactivation of thymidylate synthetase that is dependent upon prior complexation of the cofactor 5,10-methylenetetrahydrofolate. The enzyme-5-fluoro-2'-deoxyuridylate complex may be isolated on nitrocellulose membranes and is not disrupted by 6 M urea. Upon reaction of 5-fluoro-2'-deoxyuridylate with the enzyme in the presence of 5,10-methylenetetrahydr...

The title structure, [Zn(SeO(4))(CH(4)N(2)S)(3)], is isomorphous with sulfatotris(thio-urea)zinc(II). In both structures, the Zn(2+) cation is coordinated in a tetra-hedral geometry. The corresponding intra-molecular distances are quite similar except for the Se-O and S-O distances. Although the hydrogen-bonding patterns are similar, there are some differences; in the title structure all the H ...

This study evaluated in vitro the influence of enamel bleaching on bond strength to dentin. One hundred and twenty bovine incisors were divided into 12 groups (n = 10), according to adhesive system: Adper Single Bond 2 (ASB2), Prime & Bond 2.1 (PB), Adhese (AD) and Clearfil SE Bond (SE). The experimental groups were exposed to 10% carbamide peroxide for 4 hours a day over a period of 10 days. A...