Ion-exchange selectivity of anion exchange resin modified with polystyrenesulfonic acid.

In order to change the ion-exchange selectivity of anion-exchange resin, the surface of a gel-type anion exchange resin was modified with anionic polyelectrolyte, polystyrenesulfonic acid. Using this modified resin, the ion-exchange rate of nitrate was little decreased, but that of sulfate was evidently decreased. It is considered that the ion-exchange reaction of the multivalent anion is suppressed by the greater electrostatic repulsive force against the modification layer than that against the monovalent anion. Thus, this modified resin may be suitable for the selective separation of monovalent anions. The influence of the modified condition on the ion-exchange rate was examined. Furthermore, this modified resin was used to separate nitrate ions from sulfate ions in the aqueous solution.     

Stimulatory effect of red light on starch accumulation in a marine green alga,chlamydomonas sp. strain MGA161

A marine green alga,Chlamydomonas sp. strain MGA161 was cultivated under illumination of red and white lights. The growth rate under red light illumination was almost the same as that in the basic conditions under white light illumination, but red light-grown cells accumulated almost twice as much starch as white light-grown cells. Although there was a slight decrease in carbonic anhydrase activity, red light-illuminated cells had almost 2.3 times the fructose-l,6-diphos-phatase activity of white light-illuminated cells. Red light might stimulate starch accumulation by increasing the amounts of enzymes related to carbon fixation through the phytochrome system. Cells grown under red light degraded 1.6 times as much starch and produced 1.7 times as much hydrogen and 1.6 times as much ethanol compared with cells grown under white light during 12 h of dark anaerobic fermentation.     

Structure-activity study of intact porcine motilin

Biologically important sites on intact porcine motilin (pMTL) were explored using its partial peptides. The partial peptides were synthesized using Fmoc (9-fluorenylmethyloxycarbonyl) solid phase methodology, and tested for the binding activity to motilin receptor and the smooth muscle contractile activity. The results were as follows: important residues for the contractile activity were found to be Phe1, Ile4, and Tyr7, and an open space existed beyond the N-terminus between motilin and its receptor. On the model of interaction between motilin and motilin receptor evolved from these results, the three points of interaction, due to Phe1, Ile4, and Tyr7, and the presence of an open space were expected. The motilin agonist and antagonist, designed on this model, will help the inquiry into motilin associated diseases.     

Preparation and characterization of novel branched beta-cyclodextrins having beta-D-galactose residues on the non-reducing terminal of the side chains and their specific interactions with peanut (Arachis hypogaea) agglutinin

Six novel branched beta-cyclodextrins (betaCDs) having beta-D-galactose residues on the non-reducing terminal of the sugar side chains, namely 6(1),6(4)-di-O-(beta-D-galactosyl)-betaCD (10), 6-O-(beta-D-galactosyl)-betaCD (11), 6(1),6(4)-di-O-(beta-lactosyl)-betaCD (14), 6-O-(beta-lactosyl)-betaCD (15), 6(1),6(4)-di-O-(4'-O-beta-D-galactosyl-beta-lactosyl)-betaCD (18), and 6-O-(4'-O-beta-D-galactosyl-beta-lactosyl)-betaCD (19), were chemically synthesized using the trichloroacetimidate method. The reaction products were separated by HPLC on an amino column into dibranched and monobranched betaCDs. Their structures were confirmed by mass spectrometry (MS) and two-dimensional (2D) NMR spectroscopic analysis. To study the length of the sugar side chains attached to the CD ring, which leads to differences in the functions of the branched CDs, interactions of these compounds with peanut (Arachis hypogaea) agglutinin (PNA) were investigated using an optical biosensor and an inhibition assay based on hemagglutination. The results showed that all branched betaCDs interacted with PNA, and the binding affinity was 18>14>10 and 19>15>11 when the derivatives were compared on the basis of side chain length.     

Origin of stereochemical reversal in Meyers-type enolate alkylations. Importance of intramolecular Li coordination and solvent effects

[reaction: see text] The origin of exclusive exo-stereochemistry in the alkylation of Meyers-type enolate 2 has been studied. It was found that the intramolecular complex with a strong Li...O(ring) interaction (the O-complex) may be responsible as the major enolate species in tetrahydrofuran (THF). The transition state of the O-complex leading to exo-stereochemistry is found to be the most favorable process in THF.     

Carbon dioxide fixation by microalgae photosynthesis using actual flue gas discharged from a boiler

To mitigate CO₂ discharged from thermal power plants, studies on CO₂ fixation by the photosynthesis of microalgae using actual exhaust gas have been carried out. The results are as follows.

The difference between the mechanism of 67Ga accumulation and 59Fe accumulation in cultured tumor cells

It is well known that the mechanism of 67Ga accumulation into tumor cells is mediated with transferrin receptor as well as iron. The present study was designed to explore the difference between the mechanism of gallium accumulation and that of iron by using mouse leukemic cell line L5178Y. When monensin which inhibits the recycle of transferrin receptor was added to the incubated system, accumulation of 59Fe and 67Ga was clearly diminished compared with that of control. However, inhibition of 59Fe accumulation was more remarkable than that of 67Ga. Furthermore, monensin has a action of Na+ ionophore which decreases Na+ gradient between the inside and the outside of the plasma membrane. Following administration of monensin, 67Ga accumulation was diminished according to the loss of the Na+ gradient. On the other hand, following administration of valinomycin, 67Ga accumulation was not affected by the loss of the K+ gradient. From these results, it was suggested that the mechanism of 67Ga accumulation into tumor cells differed from that of 59Fe and transferrin receptor and Na+ gradient of tumor cells played an important role on 67Ga accumulation into tumor cells.     

Ab initio calculations on the clustering energies and stable structures of H(M)+ + M → H(M)2+ (M = CO and N2)

The clustering energies of the reactions, H(M)⁺+ M → H(M)⁺₂ (M = CO and N₂), were calculated by ab initio single configuration LCAO SCF MO and SCEP methods. The calculated energies are in good agreement with the experimental enthalpies.