The normalization constant of a certain invariant measure on GL n ( )

The ratio of the Tamagawa measure and a certain invariant measure on the group GL_n() is computed, where is the adèle of a division algebra D over a global field. An explicit formula of the ratio is described in terms of the special values of the zeta function of D. This formula yields (i) an explicit lower bound of the Hermite–Rankin constant _n,m(D) of D and (ii) an explicit asymptotic behavior of the distribution of rational points on Brauer–Severi variety.Mathematics Subject Classification (2000): Primary 11R52, Secondary 11H50     

Decay time shortening of fluorescence from donor-acceptor pair proteins using ultrafast time-resolved fluorescence resonance energy transfer spectroscopy

We improved an ultrafast time-resolved fluorescence resonance energy transfer (FRET) spectroscopy system and measured directly the decrease in the fluorescence decay time of the FRET signal, without any entanglement of components in the picosecond time scale from the donor-acceptor protein pairs (such as cameleon protein for calcium ion indicator, and ligand-activated GRIN-Go proteins pair). The drastic decrease in lifetime of the donor protein fluorescence under the FRET condition (e.g. a 47.8% decrease for a GRIN-Go protein pair) proves the deformation dynamics between donor and acceptor fluorescent proteins in an activated state of a mixed donor-acceptor protein pair. This study is the first clear evidence of physical contact of the GRIN-Go proteins pair using time-resolved FRET system. G protein-coupled receptors (GPCRs) are the most important protein family for the recognition of many chemical substances at the cell surface. They are the targets of many drugs. Simultaneously, we were able to observe the time-resolved spectra of luminous proteins at the initial stage under the FRET condition, within 10 ns from excitation. This new FRET system allows us to trace the dynamics of the interaction between proteins at the ligand-induced activated state, molecular structure change and combination or dissociation. It will be a key technology for the development of protein chip technology.     

Visible pulse compression to 4 fs by optical parametric amplification and programmable dispersion control

Angular dispersion of pump frequencies is shown to be an efficient mechanism for bandwidth enhancement in a noncollinear optical parametric amplifier. We demonstrate the generation of a continuous, simultaneously phase-matched 250-THz parametrically amplified spectrum. The resultant visible-near-IR signal-wave pulses were compressed to a 4-fs duration by a micromachined flexible mirror. Feedback for an iterative computer-controlled dispersion compensation algorithm is based on pulse characterization by second-harmonic generation frequency-resolved optical gating.     

Enantioselective catalysis of carbonyl-ene and Friedel–Crafts reactions with trifluoropyruvate by ‘naked’ palladium(II) complexes with SEGPHOS ligands

Chiral dicationic SEGPHOS–Pd(II) complex gives high chemical yield, (E)-olefin selectivity, anti-diastereoselectivity, along with high enantioselectivity even with less reactive mono- and 1,2-disubstituted olefins in this much less reactive ketone-ene reactions. The high levels of enantioselectivity not only in carbonyl-ene but also in Friedel–Crafts reactions stem from the effective shielding with diphenyl groups on phosphines caused by the narrow dihedral angle of metal complexes with SEGPHOS.     

2,9-dithia-1-thioxophosphabicyclo[4.3.0]nona-3,7-dienes. Precursors of new type heterodienes, 2-thioxo-1,2-thiaphospholes

The reaction of arylmethylenepinacolones, chalcones and 2-arylmethylene-1-tetralones with P₄S₁₀ in the presence of triethylamine gave the title compounds, from which 2-thioxo-1,2-thiaphospholes (phosphathiophenes) were generated by the thermolysis and reacted with acrylonitrile to give [4+2]cyclo-adducts.     

Simultaneous microanalysis of N-linked oligosaccharides in a glycoprotein using microbore graphitized carbon column liquid chromatography-mass spectrometry

We previously reported that graphitized carbon column liquid chromatography-mass spectrometry (GCC-LC-MS) is very useful for the structural analysis of carbohydrates in a glycoprotein. In this study, GCC-LC-MS was adapted for the simultaneous microanalysis of oligosaccharides. A variety of oligosaccharide alditols prepared from fetuin, ribonuclease B, and recombinant human erythropoietin were used as model oligosaccharides. The use of microbore GCC-LC-MS was found to be successful for rapid, sensitive, and simultaneous analysis of high-mannose-type, desialylated fucosyl complex-type, sialylated complex-type, and sialylated fucosyl complex-type oligosaccharide alditols. Furthermore, we demonstrate that this method is applicable to the analysis of carbohydrate heterogeneity in a glycoprotein that possesses diverse oligosaccharides. Microbore GCC-LC-MS was able to characterize high-mannose-type, hybrid-type, and complex-type oligosaccharides in tissue plasminogen activator produced from human melanoma cells in a single analysis.