Showing papers on "Pyranose published in 1971"

The biosynthesis of galactofuranosyl residues in galactocarolose.

Abstract: 1. Cell-free extracts of Penicillium charlesii G. Smith were used in a study of the biosynthesis of the galactofuranose polymer, galactocarolose. 2. UDP-glucose and UDP-galactopyranose were precursors of galactocarolose and it was shown that the galactofuranose residues in the polymer were formed from glucose without fission of the hexose carbon chain. 3. A new nucleotide, UDP-α-d-galactofuranose, was formed by the system and was a major product when polymer synthesis was inhibited by F− or Zn2+; the nucleotide was isolated and its structure determined. 4. UDP-α-d-galactofuranose was efficiently utilized for polymer synthesis and shown to be formed from the pyranose nucleotides. 5. A route for the biosynthesis of galactocarolose, involving a novel ring contraction of the hexose residue while still attached to the nucleotide, is proposed.

Studies of Carbohydrate Derivatives by Nuclear Magnetic Double Resonance. Part VI. The Identification of 13C Chemical Shifts of Methyl Resonances via the 1H–{13C} INDOR Technique

Abstract: The 13C chemical shifts of acetate- and methoxyl-methyl substituents of several pyranose carbohydrate derivatives have been measured by the 1H–{13C} INDOR technique. The chemical shifts (δ13C) of anomeric methoxyl-methyl resonances fall into two groups: for α-anomers (axial substituent), δ13C = 55.12–56.63 p.p.m.; for β-anomers (equatorial substituent), δ13C = 56.63–8.69 p.p.m. O-Acetyl-methyl shifts fall between 20.54–20.72 p.p.m. and N-acetyl-methyl shifts were detected between 22.98–23.08 p.p.m.

The deamination of pyranose amines. Part I. Equatorial amines

Abstract: The deamination of methyl 4-amino-4-deoxy-α-D-glucopyranoside with nitrous acid gives methyl α-D-glucopyranoside (major product), methyl β-L-altrofuranoside, 4,5-anhydro-D-galactose, and methyl 3-deoxy-3-formyl-α-D-xylofuranoside. Deamination of 2-amino-1,5-anhydro-2-deoxy-D-glucitol gives 1,5-anhydro-D-glucitol as the major product. Participation of the ring oxygen atom dominates the reactions of these and related compounds, in which the equatorial amino group is at C-2 or C-4.

Method for producing sugar acetals

Abstract: SUGAR ACETALS COMMONLY EMPLOYED AS INTERMEDIATES FOR THE SYNTHESIS OF OTHER COMPOUNDS USEFUL IN FOODS AND DRUGS, ARE PREPARED BY A NOVEL ONE-STEP PROCESS WHICH REACTS SUGARS CONTAINING PYRANOSE AND FURANOSE RINGS WITH A N,N-DIALKOXYALKANE IN THE PRESENCE OF AN ACID CATALYST. SEVERAL NEW SUGAR ACETALS ARE PRODUCED UTILIZING THIS PROCESS.

Untersuchung der Kinetik der Amylolyse

Abstract: Examination of the Kinetics of Amylolysis. A new theory to explain the extraordinarily strong effectiveness of enzymatic hydrolysis has been developed from the kinetic data on the starch hydrolysis catalyzed by acid or respectively by s-amylase. According to this theory the s-amylase gradually fits itself to the substrate of spiral structure. This adaption induces the development of hydrogen bonds formed in stages between side chains of the enzyme molecule. By this development the space structure of the bond to be split up or the pyranose ring is several times more easily attacked and split up as it is the case with non-deformed structure.

Methylation of reducing carbohydrates. Permethylated derivatives of melibiose [O-α-D-galactopyranosyl-(1 → 6)-D-glucopyranose]

Abstract: Methylation in methanol of α-melibiose and octa-O-acetyl-β-melibiose with ethereal diazomethane, and subsequent permethylation (methyl iodide–barium oxide), gave methyl hepta-O-methyl-β-melibiopyranoside (IV). When α-melibiose was methylated with methyl iodide and barium oxide, a mixture of furanose and pyranose isomers was obtained, from which pure methyl hepta-O-methyl-α-melibiofuranoside [methyl hepta-O-methyl-O-α-D-galactopyranosyl-(1 → 6)-α-D-glucofuranose](I) was isolated. The preparation of methyl hepta-O-methyl-β-melibiofuranoside (II) is reported.

Transfer Reaction of β-D-Glycofuranose by β-Glycosidase

Abstract: Transfer reaction of β-D-glucofuranose from phenyl β-D-glucofuranoside to methanol by almond emulsin was recognized. Extent of glucofuranosyl transfer from different aryl β-D-glucofuranoside to alcohol was determined. Influence of pH on the glucofuranosyl transfer was examined. The course of the transfer reaction was also reported. Enzymic transfer of β-D-galactofuranose and β-D-glucofuranosiduronic acid was also investigated. In view of the above facts, it was concluded that β-D-glycofuranosyl residue was transferred by β-glycosidase from phenol to alcohol and conversion of furanose ring to pyranose ring was not occured in the course of enzymic transfer reaction.

Mechanism for formation of peak with m/e 583 of trimethylsilyl derivatives of 1,6-disaccharides

Abstract: The ion with m/e 583 is formed as the result of rearrangement of the pyranose form of the ring.