Moscow-Russia-Chemical-College-Academy-Sciences-o

I. Mendeleev University of Chemical Technology of Russia, Moscow, Russia.Russian Academy of Sciences, Moscow, Russia; Institute of Antimicrobial Chemotherapy, Smolensk State Medical University, Smolensk, Russia.Smolensk, Russia; Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, Russia; State Research Center for Applied Microbiology and Biotechnology, Obolensk, Moscow Region, Russia.The genome of Acinetobacter baumannii clinical isolate, MAR-3, recovered in Russia was sequenced and found to contain a novel gene cluster at the A. baumannii K locus for capsule biosynthesis.

The gene cluster, designated KL116, included four genes for glycosyltransferases (Gtrs) and a gene for a Wzy polymerase responsible for joining oligosaccharide K units into the capsular polysaccharide (CPS). The arrangement of KL116 was a hybrid of previously described A. baumannii gene clusters, with two gtr genes and the wzy gene shared by KL37 and the two other gtr genes found in KL14. The structure of the K116 CPS was established by sugar analysis and Smith degradation, along with one- and two-dimensional 1H and 13C NMR spectroscopy. 2'-FL is composed of branched pentasaccharide K units containing only neutral sugars, with three monosaccharides in the main chain and a disaccharide side chain. The K116 unit shares internal sugar linkages with the K14 and K37 units, corresponding to the presence of shared gtr genes in the gene clusters. However, the specific linkage formed by Wzy was discrepant between K116 and the previously reported K37 CPS produced by A.

baumannii isolate NIPH146. 2'-fucosyllactose was therefore revised in this study, and the corrected Wzy linkage found to be identical to the Wzy linkage in K116. The KL116, KL14 and KL37 gene clusters were found in genomes of a variety of A. baumannii strain backgrounds, indicating their global Frequent occurrence of pre-existing alpha 2--8-linked disialic and oligosialic acids with chain lengths up to 7 Sia residues in mammalian brain glycoproteins. Prevalence revealed by highly sensitive chemical methods and anti-di-, oligo-, and poly-Sia antibodies specific for defined chain lengths.Sato C(1), Fukuoka H, Ohta K, Matsuda T, Koshino R, Kobayashi K, Troy FA 2nd, The pre-existence of alpha2--8-linked disialic acid (di-Sia) and oligosialic acid (oligo-Sia) structures with up to 7 Sia residues was shown to occur on a large number of brain glycoproteins, including neural cell adhesion molecules Matsuda, T., and Kitajima, K.

(1998) Anal. Biochem. 261, 191-197; Sato, C., Inoue, S., Matsuda, T., and Kitajima, K. (1999) Anal.

Biochem. 266, 2-9). This unexpected finding was also confirmed using a newly developed antibody prepared using a copolymer of alpha2--8-linked N-acetylneuraminyl p-vinylbenzylamide and acrylamide as an immunogen and known antibodies whose immunospecificities were determined to be di- and oligo-Sia residues with defined chain lengths. The major significance of the new finding that di- and oligo-Sia chains exist on a large number of brain glycoproteins is 2-fold. First, it reveals a surprising diversity in the number and M(r) of proteins distinct from N-CAM that are covalently modified by these short sialyl glycotopes. Second, it suggests that synthesis of di- andor oligo-Sia units may be catalyzed by alpha2--8-sialyltransferase(s) that are distinct from the known polysialyltransferases, STX and PST, which are partially responsible for The structure of the fructan sinistrin from Urginea maritima.The structure of sinistrin from red squill (Urginea maritima) was determined by methylation analysis and 13C NMR spectroscopy, using the fructans from Pucinella peisonis and quack-grass (Agropyron repens) as reference substances.

Application of the reductive cleavage method showed that, of the beta-D-fructofuranosyl residues in sinistrin, 33% were 1-linked, 19% were 6-linked, 25% were terminal, and 19% were 1,6-linked. The average dp was 31 and, of the 34% of alpha-D-glucopyranosyl residues,4% were terminal and 2.% were 6-substituted. The fructan of quack grass was also highly branched with a approximately 45. The fructan from Pucinella peisonis was slightly branched, with a dp of approximately and a (2--6)-linked backbone.An efficient synthesis of L-idose and L-iduronic acid thioglycosides and their use for the synthesis of heparin oligosaccharides.Efficient preparations of thioglycoside derivatives of L-idose and L-iduronic acid are described.

The method avoids the tedious chromatographic separations of furanose and pyranose anomeric mixtures, and affords the thioglycosides in a stereoselective manner.