Estimation of sialic acid in a sialoglycan and a sialoglycoprotein by capillary electrophoresis with in-capillary sialidase digestion

An example of application of in-capillary derivatization for CE, obtained by using the throughout-capillary format, is presented. Introduction of a sialoglycan (N-acetylneuraminyllactose) or a sialoglycoprotein (bovine serum fetuin) sample to a running buffer (pH 5.0) containing N-acetylneuraminidase followed by application of a voltage resulted in the release of N-acetylneuraminic acid (NANA) which could be estimated by CE with UV detection. Two-step application of voltages (5 and 20 kV) was proved to be more effective for rapid estimation of the released NANA. This format (modified throughout-capillary format) allowed differential estimation of the NANA present in the sample as an impurity and the NANA released from the substrate at the picomol level, and thereby reliable micro assay of the sialidase activity. It also allowed estimation of the rate constant of this enzymatic reaction.     

1,3-dimethylisoguaninium,an antiangiogenic purine analog from the sponge Amphimedon paraviridis

An antiangiogenic purine analog, 1,3-dimethylisoguaninium (1), was isolated from the ethanol (EtOH) extract of the Okinawan sponge Amphimedon paraviridis. The structure was elucidated on the basis of its spectral properties and X-ray crystallographic analysis. Compound 1 exhibited specific inhibition of the basic fibroblast growth factor (bFGF)-induced proliferation of bovine aorta endothelial cells (BAECs). Moreover, compound 1 reduced the tube formation of BAECs in a time-dependent manner.     

BIOSYNTHESIS AND ASSEMBLY OF PURPLE MEMBRANE OF HALOBACTERIUM HALOBIUM S9: LIGHT STIMULATION OF BACTERIORHODOPSIN FORMATION

Abstract— The effect of light on purple membrane biogenesis in Halobacterium halobium S9 strain was investigated. When bacteria were grown in the dark, the 570nm absorption due to bacteriorhodopsin increased more slowly than under illumination, but eventually after longer incubation, reached the same level as that seen in the illuminated culture.
Analysis of membrane fractions by sucrose density gradient centrifugation revealed that two different membrane fractions, containing purple and brown membrane could be detected in the exponential growth phase. Another fraction whose density was higher than that of purple membrane, disappeared concomitantly with the increase in purple membrane and brown membrane, indicating that it may be related to purple membrane formation.
HPLC analysis of membrane proteins showed that there was no significant difference in de novo synthesis of bacterio–opsin between dark and illuminated cultures. This led us to conclude that light stimulated retinal binding to bacterio–opsin and/or retinal biosynthesis rather than bacterio–opsin synthesis. Bacteriorhodopsin seemed to form the brown membrane fraction first, which then spontaneously reorganized into purple membrane.
When incorporated in liposomes, bacteriorhodopsin in brown membrane was found to have rather higher proton pump activity than that in purple membrane. The H⁺ pumping activity was quite heat labile. This and the CD spectra indicated that bacteriorhodopsin in brown membrane might exist without forming normal timer unit.     

Determination of traces of gallium and indium in ores by electrothermal-atomization atomic absorption spectrometry with matrix modifications

Methods were developed for the determination of gallium and indium in complex ores by electrothermal-atomization atomic absorption Spectrometry using matrix modifications. Nickel and nickel-ammonium sulfate as matrix modifier has enhanced the absorption signals for gallium and indium, respectively, eliminating the matrix interferences to allow their solutions in nitric acid to be used as calibration standards. No matrix separations are necessary. Results are quoted for a variety of black ore samples (Kuroko). The RSDs are 7.0% for gallium and 5.3% for indium at their 10 g/g levels, and the inverse sensitivities are 20 pg of gallium and 38 pg of indium for respective 1% absorption.     

Application of the stepwise clustering method for efficient drawing of biopolymer structures

The reduction of drawing time is desirable in writing a complex molecular structure by use of a plotter. The stepwise clustering method is applied to find efficient drawing paths for six structures of protein and DNA molecules. All the optimization ratios of path lengths exceed 50%, while the necessary CPU times are of the order of 0.1 second. These results show the effectiveness of the method for molecular graphics. A summary of the algorithm and other possible applications are also discussed.     

Preparation and biological activities of a bivalent poly(ethylene glycol) hybrid containing an active site and its synergistic site of fibronectin

A bivalent poly(ethylene glycol) or PEG hybrid of fibronectin-related peptides was prepared. An active site peptide (RGD) and its synergistic site peptide (PHSRN) of fibronectin were conjugated with an amino acid-type PEG (aaPEG) to form PHSRN-aaPEG-RGD. A moderate spatial array between RGD and PHSRN in fibronectin may be required for synergic activity. The bivalent hybrid exhibited potent cell spreading activity and exhibited potent anti-metastatic activity in a model of experimental metastasis with B16-BL6 cells in mice. PEG may serve as a spacer for maintaining the desired spatial array.     

Synthesis, molecular structure, and chemical reactivity of azuleno[1,2-a]acenaphthylene

The azuleno[1,2-a]acenaphthylene (1a) was prepared from 1-pyrrolidinylacenaphthylene (5) and 2H-cyclohepta[b]furan-2-one (6) by the method of the Takase-Yasunami azulene synthesis. Its ¹H and ¹³C NMR spectra indicate that 1a comprises azulene and naphthalene rather than acenaphtylene and heptafulvene in accordance with speculation drawn from a previous study of the DEPE calculations. The solid-state structure of 1a was elucidated by X-ray crystallographical analysis, indicating that 1a is nearly planar and exhibits little bond alternation as seen in the optimized structure at the MB3LYP/6-311G^∗ level of theory. All bond lengths observed by the X-ray analysis are in good agreement within 0.024 Å with those calculated. Under pyrolytic conditions 1a underwent azulene-naphthalene rearrangement to give 9 and 10. The electrophilic substitution of 1a was observed at the 7-position and the second reaction at the 3-position. The cycloaddition reaction of 1a with dimethyl acetylenedicarboxylate (DMAD) yielded the 1:1 cycloadduct with a heptalene skeleton 16a and the 1:2 cycloadduct 19, along with the substitution product 17. The X-ray structural analysis of the cycloadducts 16a and 19 is also described.     

INTERACTION OF 9-AMINOACRIDINE WITH 7-METHYLGUANOSINE AND 1,N6-ETHENOADENOSINE MONOPHOSPHATE

Abstract—Fluorescence properties of 9-aminoacridine in aqueous solutions of 7-methylguanosine (7MeG) and 1, N ⁶-ethenoadenosine monophosphate (εAMP) have been examined. It was found that fluorescence of the dye was quenched by 7MeG and εAMP as well as by unmodified nucleotides such as GMP and AMP. Quantitative analysis of the results shows that both dynamic and static quenching processes are responsible for the quenching of fluorescence.