Notable deuterium effect on the electron transfer rate of myoglobin

The electron transfer reaction of wild-type myoglobin at an electrode was significantly facilitated in a D2O buffer as compared with that in an H2O buffer, with k(0)'(H2O)/k(0)'(D2O)= 0.13, while a minimal deuterium kinetic isotope effect on the myoglobin with modification at distal histidine (His-64) was observed.     

Azetidinic amino acids: stereocontrolled synthesis and pharmacological characterization as ligands for glutamate receptors and transporters

A set of ten azetidinic amino acids, that can be envisioned as C-4 alkyl substituted analogues of trans-2-carboxyazetidine-3-acetic acid (t-CAA) and/or conformationally constrained analogues of (R)- or (S)-glutamic acid (Glu) have been synthesized in a diastereo- and enantiomerically pure form from beta-amino alcohols through a straightforward five step sequence. The key step of this synthesis is an original anionic 4-exo-tet ring closure that forms the azetidine ring upon an intramolecular Michael addition. This reaction was proven to be reversible and to lead to a thermodynamic distribution of two diastereoisomers that were easily separated and converted in two steps into azetidinic amino acids. Azetidines 35-44 were characterized in binding studies on native ionotropic Glu receptors and in functional assays at cloned metabotropic receptors mGluR1, 2 and 4, representing group I, II and III mGlu receptors, respectively. Furthermore, azetidine analogues 35, 36, and 40 were also characterized as potential ligands at the glutamate transporter subtypes EAAT1-3 in the FLIPR Membrane Potential (FMP) assay. The (2R)-azetidines 35, 37, 39, 41 and 43 were inactive in iGlu, mGlu and EAAT assays, whereas a marked change in the pharmacological profile at the iGlu receptors was observed when a methyl group was introduced in the C-4 position, compound 36 versus t-CAA. At EAAT1-3, compound 35 was inactive, whereas azetidines 36 and 40 were both identified as inhibitors and showed selectivity for the EAAT2 subtype.     

Electrochemistry of monoazahemin reconstituted myoglobin at an indium oxide electrode

Monoazahemin reconstituted myoglobin was prepared and its electrochemical behavior was studied in comparison with native myoglobin. For both myoglobins well-defined voltammograms were clearly obtained at highly hydrophilic surfaces of indium oxide electrodes. Although monoazahemin showed a more positive redox potential than hemin (measured in methanol), monoazahemin reconstituted myoglobin showed a more negative redox potential than native myoglobin in a 50 mM bis-Tris buffer solution (pH 6.5), suggesting that for both native and reconstituted myoglobins the heme environment including proximal histidine as an axial ligand of the redox center plays an important role in determining the redox potential. Also, a unique electrochemical response of cyano-monoazahemin reconstituted myoglobin was demonstrated.     

A SAXS observation of the crystallization of an Al85Y10Ni5 amorphous alloy in the supercooled liquid state

The medium-range structure of a heat-treated Al₈₅Y₁₀Ni₅ amorphous alloy was investigated by small-angle X-ray scattering, calorimetric analysis, wide-angle X-ray diffraction and transmission electron microscope measurements. It is observed that crystalline particles having a definite boundary are precipitated by annealing at supercooled liquid temperatures and that most of the precipitates consist of the Al fcc crystalline phase. The integrated intensities of the small-angle scattering and the Guinier radii of the precipitates increase on annealing for time duration <5.4 ks. However, as the annealing time becomes > 5.4 ks, the integrated intensities and the Guinier radii are invariant, i.e., growth of the precipitates ceases. After annealing for 518.4 ks, the diameters of the precipitates exhibit a narrow distribution centered around 200 Å.     

固态vander WaalsC 60膜晶格的Coulomb膨胀

利用扫描隧道显微镜观测到生长在GaAs(0 0 1 ) 2× 4表面上的固态vanderWaals C₆₀ 膜在室温下较之C₆₀ 晶体具有 1 3%的晶格膨胀 .这种膨胀是由从GaAs衬底饱和的As悬挂键上转移到C₆₀分子上的电荷之间的Coulomb作用引起的 .理论计算表明 ,平均约有 1 76个电子转移到每个C₆₀分子上 .有趣的是 ,该固态C₆₀ 膜为 (1 1 0 )取向 ,这明显不同于生长于其他半导体或金属表面上的具有 (1 1 1 )取向的六角密排C₆₀膜 .这种反常取向的薄膜是由GaAs衬底的各向异性产生的一维限制作用导致的 .通过选择不同的衬底 ,可以控制C₆₀薄膜的晶体生长     

Beweis der Integrirbarkeit gewöhnlicher Differentialgleichungssysteme nach Peano

Ohne ZusammenfassungMit einer Figurentafel     

Stereoselective pinacol coupling of chiral formylferrocene using divalent samarium triflate: preparation of a new chiral bisferrocenyl oxazoline ligand and its application to asymmetric Diels-Alder reactions

[reaction: see text] The pinacol coupling reaction of planar chiral ortho-oxazoline-substituted formylferrocene was smoothly mediated by SmI2 or Sm(OTf)3 to give the (R,R) isomer selectivity (up to 76% diastereomeric excess). The combination of Yb(OTf)3 and the (R,R)-ferrocenyl diol was revealed to be a good catalyst for the asymmetric Diels-Alder reaction of 3-acyloxazolidinone with cyclopentadiene, and the endo adduct was produced in up to 80% enantiomeric excess.