Prion proteins are key molecules in transmissible spongiform encephalopathies (TSEs), but the precise mechanism of the conversion from the cellular form (PrP C ) to the scrapie form (PrP Sc ) is still unknown. Here we discovered a chemical chaperone to stabilize the PrP C conformation and identified the hot spots to stop the pathogenic conversion. We conducted in silico screening to find compounds that fitted into a ''pocket'' created by residues undergoing the conformational rearrangements between the native and the sparsely populated high-energy states (PrP*) and that directly bind to those residues. Forty-four selected compounds were tested in a TSE-infected cell culture model, among which one, 2-pyrrolidin-1-yl-N-[4-[4-(2-pyrrolidin-1-yl-acetylamino)-benzyl]-phenyl]-acetamide, termed GN8, efficiently reduced PrP Sc . Subsequently, administration of GN8 was found to prolong the survival of TSE-infected mice. Heteronuclear NMR and computer simulation showed that the specific binding sites are the A-S2 loop (N159) and the region from helix B (V189, T192, and K194) to B-C loop (E196), indicating that the intercalation of these distant regions (hot spots) hampers the pathogenic conversion process. Dynamics-based drug discovery strategy, demonstrated here focusing on the hot spots of PrP C , will open the way to the development of novel anti-prion drugs.anti-prion compound ͉ binding sites ͉ chemical chaperone ͉ dynamicsbased drug discovery ͉ transmissible spongiform encephalopathy

The blood-brain barrier (BBB) is highly restrictive of the transport of substances between blood and the central nervous system. Brain pericytes are one of the important cellular constituents of the BBB and are multifunctional, polymorphic cells that lie within the microvessel basal lamina. The present study aimed to evaluate the role of pericytes in the mediation of BBB disruption using a lipopolysaccharide (LPS)-induced model of septic encephalopathy in mice. ICR mice were injected intraperitoneally with LPS or saline and were sacrificed at 1, 3, 6, and 24 h after injection. Sodium fluorescein accumulated with time in the hippocampus after LPS injection; this hyperpermeability was supported by detecting the extravasation of fibrinogen. Microglia were activated and the number of microglia increased with time after LPS injection. LPS-treated mice exhibited a broken basal lamina and pericyte detachment from the basal lamina at 6-24 h after LPS injection. The disorganization in the pericyte and basal lamina unit was well correlated with increased microglial activation and increased cerebrovascular permeability in LPS-treated mice. These findings suggest that pericyte detachment and microglial activation may be involved in the mediation of BBB disruption due to inflammatory responses in the damaged brain.

We have carried out high-field resistivity measurements up to 27 T in EuFe2As2 at P = 2.5 GPa, a virtually optimal pressure for the P -induced superconductivity, where Tc = 30 K. The Bc2−Tc phase diagram has been constructed in a wide temperature range with a minimum temperature of 1.6 K (≈ 0.05 × Tc), for both B ab (B PACS numbers: 74.25. Op,74.25.Dw,74.62.Fj The discovery of superconductivity in LaFeAs(O,F) at T c = 26 K 1 has inspired experimental and theoretical research on a group of FeAs-layered superconductors (SCs).2 Basically, Fe-based high-T c superconductivity 3-5 occurs when the antiferromagnetic (AF) order in the mother compounds is suppressed by means of carrier doping, 1 application of pressure (P ), 6 or isovalent substitution.7 As compared to other methods in studying such interplay between magnetism and superconductivity, pressure experiments have a significant advantage in that they are free from random impurity potentials that may distort the underlying physics of the low-lying energy states. Among the various crystal structures, tetragonal ThCr 2 Si 2 -type ("122") compounds have been investigated more intensively owing to the availability of highly-pure stoichiometric single crystals. In particular, AFe 2 As 2 (A = Sr, Eu) exhibits P -induced bulk superconductivity with T c of order 30 K. 6,8,9 In contrast, superconductivity under hydrostatic pressure is not exhibited by CaFe 2 As 2 , 10 and its occurrence in BaFe 2 As 2 has not been established definitively. 8,11A fundamental characteristic of SCs is the upper critical field B c2 . B c2 has its roots in the breakdown of Cooper pairs; hence, the B c2 −T c phase diagram provides important insights into the pairing mechanism of high-T c superconductivity. Thus far, to our knowledge, there has been no reports on B c2 for P -induced Fe-based SCs at low temperatures. This is mainly attributed to the difficulty in conducting high-pressure experiments on high-T c SCs under a high-field. In the case of SrFe 2 As 2 (T c = 30 K at 4.2 GPa), a field of 8 T brings about a small reduction in T c (i.e., to 27 K) for B ab.13 Assuming an orbitally limited case, 12 B c2 (T = 0 K) could exceed 60 T. 13 However, the low-temperature region of the B c2 curve, where paramagnetic and/or multiband effects may play important roles, 14 has not been investigated.In the case of EuFe 2 As 2 (T c = 30 K at ∼ 2.5 GPa), B c2 is relatively small, i.e., ∼16 T between 5 K and 10 K, 9 and hence can be traced down to very low temperatures. EuFe 2 As 2 is unique in that the localized Eu 2+ moments exhibit an AF order below 20 K 15-19 in addition to an AF order arising from the FeAs layers at T 0 ∼190 K. T N of the Eu 2+ moments is insensitive to pressure, and the AF order occurs in the P -induced superconducting state as evidenced by magnetic and heat capacity measurements under high-pressure.9,20-22 Despite the AF order, which is produced by a weak interlayer interaction, the dominant interaction among the Eu 2+ moments is the intralayer ferromagnetic (FM) interaction, and ...

Proteins, especially multi-domain proteins, often undergo drastic conformational changes upon binding to ligands or by post-translational modifications, which is a key step to regulate their function. However, the detailed mechanisms of such dynamic regulation of the functional processes are poorly understood because of the lack of an efficient tool. We here demonstrate detailed characterization of conformational changes of MurD, a 47 kDa protein enzyme consisting of three domains, by the use of solution NMR equipped with paramagnetic lanthanide probe. Quantitative analysis of pseudocontact shifts has identified a novel conformational state of MurD, named semi-closed conformation, which is found to be the key to understand how MurD regulates the binding of the ligands. The modulation of the affinity coupled with conformational changes accentuates the importance of conformational state to be evaluated in drug design.