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The effect of phosphorylation events on the sequence-independent binding proteins of p53 is examined using two DNA substrates, one resembling Holliday junctions and the other containing extra base bulges. Gel retardation assays showed that diphosphorylation of serine 392 in the C-terminal domain of p53 greatly reduce Holliday junction and lesion recognition.

Thephase behavior and mesoscopic inhomogeneities in the ternarysystem of tertiary butyl alcohol (TBA), water, and propylene oxide(PO) have been studied by static and dynamic light scattering, gaschromatography, mass spectrometry, and molecular dynamics simulations.Mesoscale inhomogeneities are observed in this system in a broad rangeof PO concentrations, from 0.02 to about 65 mass %, and at certainTBA/water mass ratios varying from about 3/97 to about 30/70. ThisTBA/water composition domain corresponds to a region where short-livedmicelle-like molecular clustering and thermodynamic anomalies areobserved in the TBA–water binary system. At dilute PO concentrations(0.02 to about 1 mass %) the mesoscale inhomogeneities are Browniandiffusive droplets, with a size of the order of a hundred nanometers.We hypothesize that these droplets have a hydrophobic core enrichedby oily impurities and oligomerized PO molecules. A hydrogen-bondedlayer of TBA, water, and PO molecules surrounds this hydrophobic core.At high PO concentrations (beyond 50 mass %), the interfacial curvatureof the mesoscopic inhomogeneities changes its sign and the exteriorsof these inhomogeneities become hydrophobic. The inversion of theinternal curvature may result in the formation of a spongelike bicontinuousmesoscale structure at intermediate PO concentrations. This mesostructureappears to be at a nonequilibrium state, although extremely long-lived. [ABSTRACT FROM AUTHOR]

We have resolved a long-standing issue in the discussion on the origin of the mesoscale inhomogeneities observed in aqueous solutions of tertiary butyl alcohol (TBA). We have shown that the formation of stable mesoscale particles (of about 100 nm in size) can be triggered by the addition of trace amounts of propylene oxide (an impurity expected to be present in all commercial samples of TBA) to a solution, which was previously filtered at a low temperature to remove these inhomogeneities. We hypothesize that these particles are aggregates of mixed clathrate-hydrates that are formed through the stabilization of fluctuations of the intrinsic structure in TBA aqueous solutions by the clathrate-forming ability of propylene oxide. [ABSTRACT FROM AUTHOR]