Radiation-induced emission from golden hamster embryo cells

Emission from high-energy-electron-irradiated golden hamster embryo (GHE) cells has been studied over the temperature range 12–300 K both by a one-shot-single-photon-counting method and by photocurrent measurements with an oscilloscope. Emission from the irradiated phosphate buffered saline (PBS) also has been studied. The emission spectra from PBS at 12 and 77 K show a maximum around 330 and 380 nm, respectively, which are the same spectra as those from irradiated pure H₂O. The emission from irradiated GHE consists of the new band at 480 nm in addition to the emission from H₂O. The 480 nm emission is observed at the temperature range of 12–300 K, though the emission at 300 K is much lower than that at low temperature. The 480 nm emission is ascribed to the transition from excited organic substances in GHE cells. The intensity of 480 nm emission at 300 K increases linearly with increasing irradiation-dose in the range of 11–600 Gy.     

Multiplex amplified product-length polymorphism analysis of 36 mitochondrial single-nucleotide polymorphisms for haplogrouping of East Asian populations

We present a reliable, rapid, and economical multiplex amplified product-length polymorphism (APLP) method for analyzing the haplogroup-diagnostic mitochondrial single-nucleotide polymorphisms (mtSNPs) in East Asian populations. By examining only 36 haplogroup-specific mtSNPs in the coding region by using four 9-multiplex polymerase chain reaction (PCR) and subsequent electrophoresis, we could safely assign 1815 individuals from 8 populations of Japanese, Korean, Chinese, and Germans to 45 relevant haplogroups. This multiplex APLP analysis of coding-region mtSNPs for haplogrouping is especially useful not only for molecular phylogenetic studies but also for large-scale association studies due to its rapid and economical nature. This is the first panel of mtSNPs in the coding region to be used for haplogrouping of East Asian populations.     

Palladium-catalyzed reaction of allyl carbamates; allylation of carbonucleophiles,and protection-deprotection of amines

Allylation of carbonucleophiles with allylic carbamates under neutral conditions has been studied. The C-allylation of carbonucleophile is competitive with the N-allylation of amines, and the structure of amines is crucial for the selectivity. Bulky secondary amines gave the best results. Also a new method of protection-deprotection of amines as carbamates has been developed. Smooth deprotection is possible by the palladium-catalyzed reaction of allyl carbamates with formic acid. This method is particulary useful for primary amines, including optically active amino acids.     

Direct observation of the multistep helix formation of poly-L-glutamic acids

The helix formation dynamics of poly-L-glutamic acids (PGAs) were observed by the microsecond-resolved Fourier transform infrared (FTIR) and circular dichroism (CD) spectroscopies. The helix formation of 34-residue PGA from random coil at pH (or pD for FTIR) 8.0 was initiated by a pH jump to 4.9 using the rapid solution mixer whose mixing dead time is 50 micros. The amide I' line in the time-resolved FTIR spectra exhibited the fast (<100 micros) increase of the total helical content. The time-resolved CD spectra of the same process also showed the fast (<150 micros) formation of short helical segments (5 +/- 1 residues), which was followed by the slower (<1 ms) elongation of the short helices to longer helices (>10 residues). Similar dynamics were observed for the same pH jump of approximately 190-residue PGA, although there were additional steps that made the helix formation of approximately 190-residue PGA more complex. The observed multistep helix formation is likely caused by the strong hydrogen-bonding interactions between the protonated side chains of PGAs.     

A theoretical study of the dielectric solvent effect on vicinal spin coupling constants

The dielectric solvent effect on HCCH, HCNH and HCNC spin coupling constants in ethane, tetrachloroethane and trans N-methylformamide has been calculated by finite perturbation theory based on the INDO and CNDO/2 approximations incorporating solvaton theory. The available experimental data are interpreted using the calculated variations of spin coupling constants. The effect of dielectric constant on the general form of the Karplus relation is included in the finite perturbation calculations.     

A new microbial electrode for BOD estimation

A new microbial electrode using immobilizedClostridium butyricum was prepared for biochemical oxygen demand (BOD) estimation of wastewaters. The current of the electrode was decreased with time until a steady state was reached. The steady state current was in all cases attained within 30-40 min at 37°C, and the maximum current output was obtained at 37°C and pH between 6.2 and 7.0. A linear relationship was obtained between the steady state current and BOD. The steady state current values were reproducible within ±7% of the relative error. The BOD of industrial wastewaters can be estimated by using the microbial electrode. Relative error of the BOD estimation of industrial wastewaters was within ± 10%. The current output of the microbial electrode was almost constant for 30 days.     

A free energy calculation study of the effect of H-->F substitution on binding affinity in ligand-antibody interactions

Changes in binding affinity to catalytic antibody 6D9 of chloramphenicol phosphonate derivatives (CPDs) containing H or F were investigated by performing free energy calculations based on molecular dynamics simulations. We calculated the binding free energy, enthalpy, and entropy changes (DeltaDeltaG, DeltaDeltaH, and -TDeltaDeltaS) attributable to H-->F substitution by comparing results for CPDs containing a trifluoroacetylamino group (CPD-F) or an acetylamino group (CPD-H). The calculated DeltaDeltaG, DeltaDeltaH, and -TDeltaDeltaS values were -2.9, -6.3, and 3.5 kcal mol(-1) and close to experimental values observed for a series of similar ligands, chloramphenicol phosphonates with F and H (-1.4, -3.5, and 2.1 kcal mol(-1)). Therefore, CPD-F binds more strongly to 6D9 than does CPD-H. To clarify the origin of the large difference in DeltaDeltaG, we apportioned the calculated values of DeltaDeltaG and DeltaG for the associated and dissociated states into contributions from various atomic interactions. We found that the H-->F substitution increased the binding affinity mainly by decreasing the hydration free energy and not by increasing favorable interactions with the antibody. The decreased hydration free energy of the ligand was mainly due to unfavorable coulombic interactions between the trifluoroacetylamino group and solvent waters, which increased the free energy of the dissociated state (by about 3.7 kcal mol(-1)). Also, the trifluoroacetylamino group slightly increased the free energy level of the associated state (about 0.8 kcal mol(-1)) because favorable van der Waals interactions compensated for unfavorable coulombic interactions with antibody atoms. In addition, the enthalpy and entropy changes, DeltaDeltaH and -TDeltaDeltaS (computationally -6.3 and 3.5 kcal mol(-1)), originated mainly from a decrease in hydration free energy in the dissociated state. The CPD-F and CPD-H ligands had substantially different structures in the dissociated and complexed states.     

Infrared intensity in dielectric media by an electrostatic model

A change in an infrared intensity in dielectric media is treated by an electrostatic model. The basic model is originally formalized for a dipolar liquid. The model is satisfactorily applied to the infrared intensity of the C-H stretching of chloroform, which changes 22 times large in the liquid state at -43 degrees C as in the gaseous state. A change in the infrared intensity in lithium ammonium tartrate, where a ferroelectric phase transition takes place, is analyzed on the basis of a local polarization above T(c) or a spontaneous polarization below T(c), deducing important quantities on a phase transition. A difference in the infrared intensity of the C-Br stretching of 1,10-dibromodecane between the urea clathrate and the crystalline state is analyzed by evaluating electric fields due to bond moments and oscillating dipoles. These analyses confirm the mechanism of the change in the absolute infrared intensity, which originates from an electrostatic interaction with an electric field applied to a molecule or a functional group closely related to a normal mode.     

Dithiol-mediated immobilization of CdS nanoparticles from reverse micellar system onto Zn-doped silica particles and their high photocatalytic activity

Cds nanoparticles, prepared in a reverse micellar system, were immobilized directly onto alkanedithiol-modified Zn-doped silica particles, which were themselves prepared via hydrolysis of tetraethylorthosilicate in the presence of Zn(NO(3))(2) followed by contact with dithiol molecules. The resulting CdS-Zn-SiO(2) composite was then used as a photocatalyst for the generation of H(2) from 2-propanol aqueous solution. Under UV irradiation (lambda>300 nm), a high photocatalytic activity was observed for the CdS-Zn-SiO(2) composite material. This is effected by electron transfer from the photoexcited ZnS (dithiol-bonded Zn on SiO(2)) to CdS nanoparticles. The photocatalytic activity is increased with a decrease in the number of methylene groups in the dithiol molecules, according to the rank order 1,10-decanedithiol <1,6-hexanedithiol <1,2-ethanedithiol.     

Simultaneous determination of hypoxanthine,inosine, inosine-5′-phosphate and adenosine-5′-phosphate with a multielectrode enzyme sensor

A multielectrode enzyme sensor for the simultaneous determination of adenosine-5′-phosphate (AMP), inosine-5′-phosphate (IMP), inosine (HXR) and hypoxanthine (HX)in fish meat was developed by assembling four enzyme sensors for AMP, IMP, HXR and HX in a flow cell. These compounds were determined from oxygen consumption according to the following reactions: AMP $\text{AD}$ IMP $\text{NT}$ HXR $\text{NP, PO}{}^{\mathrm{3?}}{}_4$ HX $\text{XO, O}{}_2$ Uric acid where AD is AMP deaminase, NT is 5′-nucleotidase, NP is nucleoside phosphorylase and XO is xanthine oxidase. Enzymes were covalently bound to a membrane prepared from cellulose triacetate, 1,8-diamino-4-aminomethyloctane and glutaraldehyde. Sensors for HX, HXR, IMP and AMP were prepared by attaching membranes of XO, XONP, XO NPNT, and of XONPNT and AD, respectively, to four oxygen electrodes. Samples extracted from sea bass, bream, flounder, abalone and arkshell were analyzed within 5 min, from the simultaneous response curves of the four electrodes. Results obtained by the multisensor system were in good agreement with those determined by each single electrode.