52 research outputs found
Bioorganic synthesis of a recombinant HIV-1 fusion inhibitor, SC35EK, with an N-terminal pyroglutamate capping group.
The bioorganic synthesis of an end-capped anti-HIV peptide from a recombinant protein was investigated. Cyanogen bromide-mediated cleavage of two Met-Gln sites across the target anti-HIV sequence generated an HIV-1 fusion inhibitor (SC35EK) analog bearing an N-terminal pyroglutamate (pGlu) residue and a C-terminal homoserine lactone (Hsl) residue. The end-capped peptide, pGlu-SC35EK-Hsl, had similar bioactivity and biophysical properties to the parent peptide, and an improved resistance to peptidase-mediated degradation was observed compared with the non-end-capped peptide obtained using standard recombinant technology
Orbital-based Scenario for Magnetic Structure of Neptunium Compounds
In order to understand a crucial role of orbital degree of freedom in the
magnetic structure of recently synthesized neptunium compounds NpTGa_5 (T=Fe,
Co, and Ni), we propose to discuss the magnetic phase of an effective
two-orbital model, which has been constructed based on a j-j coupling scheme to
explain the magnetic structure of uranium compounds UTGa_5. By analyzing the
model with the use of numerical technique such as exact diagonalization, we
obtain the phase diagram including several kinds of magnetic states. An
orbital-based scenario is discussed to understand the change in the magnetic
structure among C-, A-, and G-type antiferromagnetic phases, experimentally
observed in NpFeGa_5, NpCoGa_5, and NpNiGa_5.Comment: 18 pages, 8 figures, to appear in New Journal of Physic
Competitive Binding Assay with an Umbelliferone-Based Fluorescent Rexinoid for Retinoid X Receptor Ligand Screening
Ligands for retinoid X receptors (RXRs), "rexinoids", are attracting interest as candidates for therapy of type 2 diabetes and Alzheimer's and Parkinson's diseases. However, current screening methods for rexinoids are slow and require special apparatus or facilities. Here, we created 7-hydroxy-2-oxo-6-(3,5,5,8,8-pentamethyl-5,6,7,8-tetrahydronaphthalen-2-yl)-2H-chromene-3-carboxylic acid (10, CU-6PMN) as a new fluorescent RXR agonist and developed a screening system of rexinoids using 10. Compound 10 was designed based on the fact that umbelliferone emits strong fluorescence in a hydrophilic environment, but the fluorescence intensity decreases in hydrophobic environments such as the interior of proteins. The developed assay using 10 enabled screening of rexinoids to be performed easily within a few hours by monitoring changes of fluorescence intensity with widely available fluorescence microplate readers, without the need for processes such as filtration
Direct observation of quasi-particle band in CeIrIn: Angle-resolved photoemission spectroscopy study
We have performed a high-resolution angle resolved Ce 4 resonant
photoemission experiment on the heavy fermion superconductor CeIrIn. We
have observed a quasi-particle band which has an energy dispersion of
meV in the Ce 4 on-resonance spectra. The result suggests that although the
4 spectra are dominated by the localized/correlated character, the small
itinerant component is responsible for the superconductivity in this compound.Comment: 5 pages, 3 figure
Identification of minimal sequence for HIV-1 fusion inhibitors.
Emergence of multi-drug resistant HIV-1 is a serious problem for AIDS treatment. Recently, the virus-cell membrane fusion process has been identified as a promising target for the development of novel drugs against these resistant variants. In this study, we identified a 29-residue peptide fusion inhibitor, SC29EK, which shows activity comparable to the previously reported inhibitor SC35EK. Some residues in SC29EK not required for interaction with virus gp41 heptad repeat 1 (HR1) were replaced with a non-proteinogenic amino acid, 2-aminoisobutyric acid (Aib), to stabilize the alpha-helix structure and to provide resistance to peptidases
Fully gapped superconductivity with no sign change in the prototypical heavy-fermion CeCu2Si2
In exotic superconductors including high- copper-oxides, the
interactions mediating electron Cooper-pairing are widely considered to have a
magnetic rather than the conventional electron-phonon origin. Interest in such
exotic pairing was initiated by the 1979 discovery of heavy-fermion
superconductivity in CeCuSi, which exhibits strong antiferromagnetic
fluctuations. A hallmark of unconventional pairing by anisotropic repulsive
interactions is that the superconducting energy gap changes sign as a function
of the electron momentum, often leading to nodes where the gap goes to zero.
Here, we report low-temperature specific heat, thermal conductivity and
magnetic penetration depth measurements in CeCuSi, demonstrating the
absence of gap nodes at any point on the Fermi surface. Moreover,
electron-irradiation experiments reveal that the superconductivity survives
even when the electron mean free path becomes substantially shorter than the
superconducting coherence length. This indicates that superconductivity is
robust against impurities, implying that there is no sign change in the gap
function. These results show that, contrary to long-standing belief, heavy
electrons with extremely strong Coulomb repulsions can condense into a
fully-gapped s-wave superconducting state, which has an on-site attractive
pairing interaction.Comment: 8 pages, 5 figures + Supplement (3 pages, 5 figures
Ab Initio Molecular Orbital Investigation of a Precursor in Ethylene Biosynthesis: Proton Transfer in a Cluster of 1-Aminocyclopropane-1-carboxylic Acid and Water
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