Showing papers on "Pyranose published in 1978"

Glucuronic acid conjugates of bilirubin-IXα in normal bile compared with post-obstructive bile. Transformation of the 1-O-acylglucuronide into 2-, 3-, and 4-O-acylglucuronides

Abstract: Structures have been determined for bilirubin-IXα conjugates in freshly collected bile of normal rats, dogs and man and in post-obstructive bile of man and rats. The originally secreted conjugate has been characterized as azopigment (I), i.e. a 1-O-acyl-β-d-glucopyranuronic acid glycoside. Conversion of the acetylated methyl ester of azopigment (I) into methyl 2,3,4-tri-O-acetyl-1-bromo-1-deoxy-β-d-glucopyranuronate (V) indicates the pyranose ring structure for the carbohydrate and a C-1 attachment for the bilirubin-IXα acyl group. Alternative procedures for deconjugation of azopigment (I) and its derivatives are also described. In post-obstructive bile, the 1-O-acylglucuronide is converted into 2-, 3- and 4-O-acylglucuronides via sequential intramolecular migrations of the bilirubin acyl group. The following approach was utilized. (1) The tetrapyrrole conjugates were cleaved to dipyrrolic aniline and ethyl anthranilate azopigments, and the azopigments were separated as the acids or methyl esters. (2) The isomeric methyl esters were characterized by mass spectral analysis of the acetates and silyl ethers. (3) The free glycosidic function was demonstrated by 1-oxime and 1-methoxime derivative formation. (4) The position of the dipyrrolic O-acyl group was determined for the methyl esters by protecting the free hydroxyl groups of the glucuronic acid moieties as the acetals formed with ethyl vinyl ether and by further conversion of the carbohydrates into partially methylated alditol acetates. These were analysed by using g.l.c.–mass spectrometry. The relevance of the present results with regard to previous reports on disaccharidic conjugates is discussed. Details of procedures for the formation of chemical derivatives for g.l.c. and mass spectrometry have been deposited as Supplementary Publication SUP 50081 (15 pages) at the British Library Lending Division, Boston Spa, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1978), 169, 5.

The Structure and Synthesis of Cytokinin Metabolites. 1. The 7- and 9-β-D-Glucofuranosides and Pyranosides of Zeatin and 6-Benzylaminopurine

Abstract: The structures of the major stable plant metabolites of the cytokinins zeatin and 6-benzylaminopurine have been confirmed by synthesis to be 7- and 9-β-D-glucopyranosides. The small quantities of metabolites initially isolated (< 100 μg) precluded assignment of the glucose ring size or configuration of the anomeric linkage so that synthesis of both the furanose and pyranose forms of 7-β-D- and 9-β-D-glucosylzeatin and 6-benzylaminopurine was undertaken which allowed direct u.v., m.s. and t.l.c. comparison with the metabolites. Numerous synthetic routes to the unusual 7-glucosides of the two cytokinins were explored, the most successful utilizing a one-pot pyrimidine ring closure of an imidazole derivative to afford directly in high yield the required 7-glucosides of zeatin and 6-benzylaminopurine.

Acceptor Specificity of the Transglycosylation Catalyzed by Cyclodextrin Glycosyltransferase

Abstract: The structural features of the sugars required as an acceptor of cyclodextrin glycosyl-transferases from Bacillus megaterium and B. macerans were investigated using 22 kinds of monosaccharides and their derivatives. It is concluded on the basis of the experimental results that the requirement for an acceptor of the intermolecular transfer reaction catalyzed by this enzyme is the pyranose structure having the same configurations of the free C2-, C3- and C4- hydroxy 1 groups as D-glucopyranose. The reaction products of the B. megaterium enzyme from starch and 2-deoxy-D-glucose, a poor acceptor, were analyzed by paper chromatography. The main product was isolated and identified by the chemical and enzymatic methods as 4-O-α-D-glucopyranosyl-2-deoxy-D-glucose. The products contained a series of ordinary maltooligo- saccharides besides a series of maltooligosaccharides each terminated by a single 4-O-α-D-glucosyl-2-deoxy-D-glucose residue at the reducing end.

Sugar equilibria. Observation of a septanose anomer

Abstract: D-Idose at equilibrium in aqueous solution at 37 °C contains 1·6% of a septanose anomer in addition to the furanose and pyranose anomers.

Male fertility-inhibiting compositions of 6-chlorodeoxy-saccharides

Abstract: A male fertility-inhibiting composition in unit dosage form, contains as an active ingredient a 6-chlorodeoxy-saccharide containing a pyranose or furanose ring of the formula ##STR1## where A represents the remainder of the pyranose or furanose ring, and has the formula C 4 H 7 O 4 X (where X represents a hydrogen atom or another pyranose or furanose ring) in association with a physiologically acceptable carrier or excipient. The saccharide preferably contains a pyranose ring or furanose ring of the formula ##STR2## Also a method of controlling fertility in men or male animals comprises administering thereto a 6-chlorodeoxy-saccharide as defined above.