A new method is presented for the identification of oligosaccharides obtained by enzymatic digestion of hyaluronan (HA) with bacterial hyaluronidase (E.C. 4.2.2.1, from Streptomyces hyalurolyticus) using matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOFMS). Mixtures containing HA oligosaccharides of tetrasaccharide (4-mer)-34-mer were analyzed using this me...

Spin-coupled theory is applied to the n electrons of the 1,3-dipoles diazomethane, fulminic acid, and nitrone, and to the inorganic molecules Og, N,O, and NO,. The linear molecules are treated as planar species, in the spirit of 1,3-dipoles taking part in cycloaddition reactions as systems with four n electrons. A very simple, albeit unexpected picture arises for the bonding in these n-electron...

Water soluble organic compounds (WSOC) in aerosol samples collected in the Amazon Basin in a period encompassing the middle/late dry season and the beginning of the wet season, were investigated by H NMR spectroscopy. HiVol filter samples (PM2.5 and PM>2.5) and size-segregated samples from multistage impactor were subjected to H NMR characterization. The H NMR methodology, recently developed fo...

Pyrolysis-gas chromatography in the presence of tetramethylammonium hydroxide (TMAH) was applied to the determination of the ratio of the abundances of the syringyl beta-aryl ether subunits to those of the guaiacyl equivalents (S/G) in lignin. Diazomethane-methylated kenafs (Hibiscus cannabinus and Hibiscus sabdariffa) and beech (Fagus crenata) in situ lignins were employed. Relative abundances...

The Friedel-Crafts reaction with 3-(3-methoxyphenyl)-3-(trifluoromethyl)-3H-diazirine and optically active N-TFA-Asp(Cl)-OMe in triflic acid afforded homophenylalanine derivatives without any loss of the optical purity.

Chlorine has been widely used to kill disease-causing microbes in drinking water. During the disinfection process, organic and inorganic material in source waters can combine with chlorine and certain other chemical disinfectants to form disinfection by-products. The kind of disinfectant used can produce different types and levels of disinfectant byproducts in the drinking water, such as trihal...

Conjugated linoleic acid (c9, t11 CLA) is a dietary fatty acid produced mainly by ruminant animals and exhibits promising health-promoting biological effects. For lipid fatty acid composition analyses, including CLA, lipids must be pre-treated so that the free and esterified fatty acids (triacylglycerols, phospholipids, etc) are available for determination. The most common treatments involve fa...

Five cyclic nitrosamines, nitrosoazetidine, nitrosopyrrolidine, nitrosopiperidine, nitrosomorpholine, and dinitrosopiperazine, labeled with deuterium and tritium, were injected into rats and then the nucleic acids of the liver were examined for the presence of alkylated bases derived from the nitrosamines. A semiquantitative mass spectrometric method able to detect 25 ng of a base was used. No ...

The spectacular heterogeneity of a complex protein mixture from biological samples becomes even more difficult to tackle when one's attention is shifted towards different protein complex topologies, transient interactions, or localization of PPIs. Meticulous protein-by-protein affinity pull-downs and yeast-two-hybrid screens are the two approaches currently used to decipher proteome-wide intera...