Thomas C.-Y. Hsieh

Synthesis of homodinuclear macrocyclic complexes of lanthanides and phenolic schiff bases

Abstract Successful syntheses of the first examples of homodinuclear macrocyclic lanthanide complexes are reported. The complexes were obtained as compounds of the 2:2 Schiff base formed by condensing 2,6-diformyl-p-cresol and triethylenetetramine (L7) by a template procedure using lanthanide nitrates and perchlorates. When reactant methanolic solutions were concentrated the complexes were deposited as yellow or orange microcrystalline precipitates, Ln2L7(NO3)4sigma; nH2O or Ln2L7(NO3)4tau; x(OH)x, x = 1 or 2, whereas solutions diluted three times deposited complexes as flaky off-white crystalline precipitates of light lanthanides. The orange Ln2L7(NO3)2(OH)2 complexes can be converted in quantitative yield to the off-white flaky form of Ln2L7(NO3)4sigma; nH2O by refluxing them in methanolic solution containing triethylenetetramine and a three-fold excess of Ln(NO3)3. The complexes were characterized by elemental analysis, fast atom bombardment mass spectrometry, UV-Vis and infrared spectroscopy and thermogravimetry. Interesting and mostly new polyatomic oxo clusters, e.g. Ln2O3+, Ln3O4+, Ln4O6+, Ln5O7+, were dominant in the mass spectra but are treated in detail elsewhere.

Structures of the asparagine-linked sugar chains of laminin

This investigation describes the isolation and characterization of oligosaccharides of the basement membrane glycoprotein, laminin. Pronase-released glycopeptides of isolated laminin, from a mouse Engelbreth-Holm-Swarm tumor, were fractionated using a combination of gel permeation chromatography and Con A-Sepharose affinity chromatography. The glycopeptides were analyzed for sugar linkage patterns by methylation analysis. Glycopeptides and hydrazine-released oligosaccharides were further analyzed using endo-beta-galactosidase, endo-beta-N-acetylglucosaminidase H and specific exoglycosidases in conjunction with calibrated gel permeation chromatography. Based on these experiments, murine tumor laminin was shown to contain asparagine-linked oligosaccharides with the following structures: bi-, tri- and tetraantennary complex-type oligosaccharides; polylactosaminyl side chains containing Gal(beta 1----4)GlcNAc(beta 1----3) repeating units attached to the trimannose core portion of the bi-, tri- and tetraantennary complex-type oligosaccharides; unusual complex-type oligosaccharides terminated at the nonreducing end with sialic acid, alpha-galactose, beta-galactose and beta-N-acetylglucosamine; alpha-galactosyl residues linked to N-acetyllactosamine sequences; high-mannose-type oligosaccharides. These results, in conjunction with analytical data, indicate that most of the carbohydrate of this laminin is N-linked to asparagine and that there are about 43 such N-linked oligosaccharides per laminin molecule.

Foliage volatiles of two rice cultivars

Abstract Volatiles of two rice varieties (‘Mars’ and PI346833) were collected from seedlings by dynamic headspace sampling and trapping on Tenax TA. Thermal desorption and cryogenic focusing methods were used to introduce the volatiles onto the column for GC-MS analysis. Twenty-eight compounds were identified. Hexanal, (E)-2-hexenal, (Z,Z)- and (E,E)-2,4-heptadienal represent the major constituents of both varieties. These aldehydes comprise more than 50% of total volatiles within both varieties. The variety ‘Mars’ contained a larger number and greater quantities (17- to 46-fold) of volatile compounds than the variety P1346833.

[13] Inositol-containing sphingolipids

Publisher Summary Glycophosphosphingolipids (GPSs) are membrane glycolipids containing a phosphodiester linkage between inositol and ceramide. The structure, “inositol (1-O)-phosphoryl-(O-1)ceramide” constitutes a common core. This chapter discusses some known glycophosphophingolipids. There is also a discussion of the procedure of isolation of a glycophosphosphingolipid fraction from plants. There is a description of the production of a carboxyl-reduced oligosaccharide mixture from the glycophosphoceramide concentrate. To isolate major fractions of the oligosaccharides, gel permeation chromatography on Bio-Rad P gels is used, effectively separating oligo saccharide fractions up to 10 sugars in length. Several methods in high-performance liquid chromatography (HPLC) can be utilized for further purification of the oligosaccharides, including reversed-phase separation of the acetylated derivatives and amino-derivatized normal-phase chromatography on silica gel. Detection methods include (1) benzoylation of the amino group on the glucosamine, (2) use of fluorescamine or o-phthaldehyde to synthesize a fluorophore on the glucosamine in glucosamine-containing GPSs for fluorescence detection of the molecules, and (3) use of tritiated acetic anhydride for radiolabeling of the aminosugar. High-performance thin-layer chromatography can complement these methods. There is also some discussion in the chapter about the new methods of sequence determination using fast atom bombardment mass spectrometry.

Volatile compounds from leaves of Ceratiola ericoides by dynamic headspace sampling

Abstract Ceratiola ericoides is a shrub endemic to the Florida scrub community and has been investigated in conjunction with studies of allelopathic interactions that affect members of the adjacent sandhill community. Headspace volatiles of C. ericoides leaves collected in spring, summer and autumn were adsorbed on Tenax TA, thermally desorbed, cryogenically refocused, and identified by GC-MS. In spring leaves, hydrocarbons were most prevalent, while alcohols, aldehydes and ketones were most abundant in summer leaves. Esters were the major components in autumn leaves.

Stability trends and fragmentation patterns of gaseous yttrium oxide clusters studied by fast atom bombardment tandem mass spectrometry

Abstract The fragmentation patterns of yttrium oxide cluster species YO+, Y2O2+, Y2O3+, Y3O4+, Y4O6+, Y5O7+, Y6O8+ and Y7O10+ were investigated at collision energies 30–110 and 170 eV by fast atom bombardment tandem mass spectrometry. The collision activated dissociation (CAD) spectra obtained revealed higher thermodynamic stability for the clusters of general formula YαO(3α−1)/2+, where a is an odd number (e.g. YO+, Y3O4+, Y5O7+, Y7O10+) which are also the preferred CAD products for all oxide clusters studied. These most stable oxides are constituted by trivalent yttrium only whereas those containing formally tetravalent yttrium YaO3a/2+, (where a is even) e.g. Y2O3+ and Y4O6+, are extremely unstable. The clusters YaO(3a−2)/2+, (where a is even) containing divalent yttrium, e.g. Y2O2+ and Y6O8+, have considerable stability but their CAD products are again the thermodynamic products YaO(3a−1)/2+. Electronic structures appear to have overriding significance in determining the thermo- dynamic stabilities of the oxide cluster species.

Novel gaseous polyatomic binary and ternary lanthanide oxides

Abstract A variety of novel gaseous polyatomic binary and ternary oxides were observed at ambient temperature arising from lanthanide (Ln) nitrate Schiff base complexes, simple salts and sesquioxides, in an FAB mass spectrometer. The new binary oxides (as singly positive ions) detected are Ln2O3, Ln3O3, Ln3O4, Ln4O4, Ln4O5, Ln4O6, Ln5O6, Ln5O7, Ln5O8, Ln6O8, Ln6O9, Ln7O10, Ln8O11, Ln8O12 and Ln9O13; the ternary gaseous oxides are CeEuO2, CeEu2O3 and Ce2EuO4, LaYbO2, La2YbO4 and LaYb2O4; NdHoO3, Nd2HoO4, and NdHo2O4; YTmO3; YxTm3−xO4, x=1−2; YxTm4−xO6, x=1−3; YxTm5−xO7, x=1−4; YxTm6−xO9, x=1−5. Some of these oxides show the lanthanide cations in unusual oxidation states. Gadolinium-gallium ternary oxides, GdGaO2, GdGaO3 and Gd2GaO4 were also detected. The FAB MS environment is significantly reducing, yielding a homologous series EunOn where Eu2+ is dominant (E°(Eu3+/Eu2+)=−0.35 V) and no gallium or indium oxides (E°(M3+/M°=−0.34 V (In), −0.53 V (Ga)) were formed. The stoichiometry of the polylanthanide ternary oxides formed is determined largely by the chemistry of the major metallic component. The gaseous polyatomic oxides are probably formed through a reductive condensation process involving primary species Ln+ and LnO+ formed when the rare earth compounds are struck by fast Xe atoms. The demonstrated possibility of double component oxide formation broadens the number and types of gaseous lanthanide oxides which are accessible.

Release of Complex Carbohydrates into Culture Medium by Cultured Hamster Cells

Publisher Summary This chapter explores the release of complex carbohydrates into culture medium by cultural hamster cells. In a study described in the chapter, normal, secondary fibroblasts of hamster embryo (HE 1) were labeled with [3H]glucosamine for either 24 or 48 h, washed extensively with unlabeled medium, and allowed to release labeled compounds into the culture medium for 48 h, while subconfluent and growing. Sepharose 6B gel-filtration of the labeled products in the medium revealed three zones of eluate, namely exclusion volume peak, intermediate mol. wt. peaks, and low mol. wt. peak. Comparison—qualitatively and quantitatively—of the uptake of [3H] glucosamine and the release of labeled compounds by normal cells and several transformed lines shows remarkable similarity, with significant differences observed only in the ion-exchange behavior of Zone 3 labeled material.