Macromolecular synthesis from saccharic lactones. Ring-opening polyaddition of D-glucaro- and D-mannaro-1,4:6,3-dilactones with alkylenediamines

Ring-opening polyaddition of a saccharic acid dilactone prepared from D-glucose, D-glucaro-1,4 : 6,3-dilactone, with several alkylenediamines proceeded at room temperature with no catalyst. The resulting new polyamides carrying many pendant hydroxyl groups, poly(alkylene D-glucaramide)s, were more amorphous and hydrophilic than the corresponding nylons having no hydroxyl groups, and were hydrolyzed more easily than the latter in an acidic condition. The ring-opening ability of D-mannaro-1,4:6,3-dilactone, which was another saccharic acid dilactone obtained from D-mannitol, was found to be lower than that of the D-glucaric analogue. © 1993 John Wiley & Sons, Inc.     

Frequency response of the glucose sensor based on immobilized glucose oxidase membrane

Frequency response of the glucose sensor based on the immobilized glucose oxidase membrane was investigated experimentally by giving the sinusoidal change of glucose concentration to the glucose sensor and observing its output signal. Observed values of gains and phase lags of the frequency response of the glucose sensor followed the frequency response model of the first-order with dead time; The time constant and also the dead time were estimated and found to decrease as the amount of enzyme immobilized in the membrane increased and the thickness of the membrane decreased.

     

A reversible near-infrared fluorescence probe for reactive oxygen species based on Te-rhodamine

We have designed and synthesized a reversible near-infrared (NIR) fluorescence probe, 2-Me TeR, for reactive oxygen species (ROS), utilizing the redox properties of the tellurium (Te) atom. 2-Me TeR is oxidized to fluorescent 2-Me TeOR by various ROS, while the generated 2-Me TeOR is quickly reduced in the presence of glutathione to regenerate 2-Me TeR. This redox-induced reversible NIR-fluorescence response of 2-Me TeR allowed us to detect the endogenous production of ROS and subsequent homeostatic recovery of the intracellular reductive environment in hydrogen peroxide-stimulated HL-60 cells. This probe is expected to be useful for monitoring the dynamics of ROS production continuously in vivo.     

A pair-excitation MCSCF calculation based on CNDO/INDO approximation I

Second-order multiconfigurational self-consistent field (MCSCF ) calculation has been programmed on the basis of CNDO /INDO molecular orbital bases, in which the configuration space employed is restricted within pair-excitations. Test calculations have been carried out for 17 small molecules. All the MCSCF ground states of these molecules have been successfully converged to their respective optimal states by employing a simple weighting scheme. This procedure provides a great savings in computer time. The MCSCF calculation on azetidine required only 27 min on a HITAC M-680H. The MCSCF energies of HF, F₂, and BH show improved behaviors up to large atomic distances (～7au).     

Spectrometric determination of various metals by high-frequency plasma torch

Summary Several analytical conditions and detection limits of various metal elements were examined with regard to the determination of these elements by photoelectric spectrometry in the combination of high-frequency plasma torch apparatus and Ebert-type grating spectrometer (GE-340), using nitrogen as the carrier gas. All the calibration curves for the elements showed good linearity and standard deviations of calcium, zinc, tin, lead, and bismuth were in the range of 1.0–3.2%. It was found that, among the various elements, aluminium, zinc, tungsten, and lead, which are difficult to be determined by flame-spectrometric analysis, can be determined with good sensitivity and high precision by the present method.

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Zusammenfassung Zur spektrometrischen Bestimmung verschiedener Metalle wird eine Kombination von hochfrequenter Plasmaflamme und Gitterspektrometer vom Ebert-Typ (GE-340) benutzt, wobei Stickstoff als Trägergas dient. Alle Eichkurven weisen eine gute Linearität auf; die Standardabweichungen für Ca, Zn, Sn, Pb und Bi liegen im Bereich von 1,0 bis 3,2%. Al, Zn, W und Pb, deren Bestimmung nach der flammenspektrometrischen Methode Schwierigkeiten bereitet, können mit Hilfe des beschriebenen Verfahrens mit guter Empfindlichkeit und hoher Genauigkeit bestimmt werden.

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Dedicated to Prof. Dr. H.Kaiser on his 60th birthday.     

Direct-reading, time-resolving technique in emission spectroscopy and its application to the analysis of iron, steel and iron ores

Summary An attempt of the time-resolution of emission spectra was carried out using a simple pulse generator by impressing a gate pulse on the dynodes of a photomultiplier tube in the direct-reading spectrometer. Examinations were made on the variation of the intensity of spectral line with time in various atmospheres and it was confirmed that the after-glow is the longest in an argon atmosphere.The possibility of avoiding the effect of an interfering spectral line lying close to the analytical line was examined and this was proved to be possible with the analytical line of Si I 2881.58 å and the interfering line of Cr II 2881.93 å. The analytical line of calcium, Ca II 3933.67 å, is interfered by Fe I 3933.61 å and the effect of the spectral line of iron was avoided by the use of the time-resolving technique. This permitted the rapid determination of 0.0010.1% of calcium in iron ores by the direct-reading spectrographic analysis.

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Zusammenfassung Ein Versuch der zeitlichen Auflösung von Emissionsspektren wurde durchgeführt unter Verwendung eines einfachen Impulsgenerators, indem man den Eröffnungsimpuls auf die Dynoden eines Photovervielfachers in einem direktschreibenden Spektrometer überlagert. Untersucht wurde die VerÄnderung der LinienintensitÄt in verschiedenartigen AtmosphÄren. Man konnte bestÄtigen, da\ das Nachglimmen in ArgonatmosphÄre am lÄngsten dauert.Auch die Möglichkeit der Vermeidung der Störung durch benachbarte Spektrallinien wurde untersucht und gefunden, da\ die Vermeidung der Störung bei der Linie Si I 2881,58 å und der Störlinie Cr II 2881,93 å möglich ist. Die Analysenlinie Ca II 3933,67 å wird durch die Linie Fe I 3933,61 å gestört, was durch die Zeitauflösungstechnik vermieden wird. Dadurch wird es möglich, 0,001–0,1% Calcium in Eisenerzen durch direktschreibende spektrographische Analyse zu bestimmen.

     

Fluorescence probe for lysophospholipase C/NPP6 activity and a potent NPP6 inhibitor

Nucleotide pyrophosphatases/phosphodiesterases (NPPs) are ubiquitous membrane-associated or secreted ectoenzymes that have a role in regulating extracellular nucleotide and phospholipid metabolism. Among the members of the NPP family, NPP1 and -3 act on nucleotides such as ATP, while NPP2, -6, and -7 act on phospholipids such as lysophosphatidylcholine and sphingomyelin. NPP6, a recently characterized NPP family member, is a choline-specific glycerophosphodiester phosphodiesterase, but its functions remain to be analyzed, partly due to the lack of highly sensitive activity assay systems and practical inhibitors. Here we report synthesis of novel NPP6 fluorescence probes, TG-mPC and its analogues TG-mPC(3)C, TG-mPC(5)C, TG-mPENE, TG-mPEA, TG-mPhos, TG-mPA, TG-mPMe, and TG-mPPr. Among the seven NPPs, only NPP6 hydrolyzed TG-mPC, TG-mPC(3)C, and TG-mPENE. TG-mPC was hydrolyzed in the cell lysate from NPP6-transfected cells, but not control cells, showing that it is suitable for use in cell-based NPP6 assays. We also examined the usefulness of TG-mPC as a fluorescence imaging probe. We further applied TG-mPC to carry out high-throughput NPP6 inhibitor screening and found several NPP6-selective inhibitors in a library of about 80,000 compounds. Through structure-activity relationship (SAR) analysis, we identified a potent and selective NPP6 inhibitor with an IC(50) value of 0.21 μM. Our NPP6-selective fluorescence probe, TG-mPC, and the inhibitor are expected to be useful to elucidate the biological function of NPP6.