Aldose

About: Aldose is a research topic. Over the lifetime, 1270 publications have been published within this topic receiving 27197 citations. The topic is also known as: aldoses.

Studies of the Pfeiffer effect induced in tris(pyridine-2,6-dicarboxylato)terbate(III) by monosaccharide aldose sugars

Abstract: Optical activity has been induced in racemic mixtures of [Tb(pydca)3]3–(pydca = pyridine-2,6- dicarboxylate) upon formation of outer-sphere complexes with monosaccharide aldoses, and studied by means of circularly polarized luminescence spectroscopy. No optical activity could be observed upon addition of D-glyceraldehyde to a solution of [Tb(pydca)3]3–, implying that the presence of a hemiacetal-ring oxygen is necessary for occurrence of the outer-sphere association. The sign of the induced optical activity was found to vary with the identity of the sugar used, but a correlation was established between the configuration at carbon 4 of the sugars (when these were present in the pyranose ring form) and the predominant [Tb(pydca)3]3– enantiomer. This suggests that an association process does indeed lead to the observed Pfeiffer effects, and that the forces leading to the formation of the outer-sphere complexes are rather specific in nature.

Enzymatic production of three 6-deoxy-aldohexoses from l-rhamnose

Abstract: 6-Deoxy-L-glucose, 6-deoxy-L-altrose, and 6-deoxy-L-allose were produced from L-rhamnose with an immobilized enzyme that was partially purified (IE) and an immobilized Escherichia coli recombinant treated with toluene (TT). 6-Deoxy-L-psicose was produced from L-rhamnose by a combination of L-rhamnose isomerase (TT-PsLRhI) and D-tagatose 3-epimerase (TT-PcDTE). The purified 6-deoxy-L-psicose was isomerized to 6-deoxy-L-altrose and 6-deoxy-L-allose with L-arabinose isomerase (TT-EaLAI) and L-ribose isomerase (TT-AcLRI), respectively, and then was epimerized to L-rhamnulose with immobilized D-tagatose 3-epimerase (IE-PcDTE). Following purification, L-rhamnulose was converted to 6-deoxy-L-glucose with D-arabinose isomerase (TT-BpDAI). The equilibrium ratios of 6-deoxy-L-psicose:6-deoxy-L-altrose, 6-deoxy-L-psicose:6-deoxy-L-allose, and L-rhamnulose:6-deoxy-L-glucose were 60:40, 40:60, and 27:73, respectively. The production yields of 6-deoxy-L-glucose, 6-deoxy-L-altrose, and 6-deoxy-L-allose from L-rhamnose were 5.4, 14.6, and 25.1%, respectively. These results indicate that the aldose isomerases used in this study acted on 6-deoxy aldohexoses.

Preparation and polymer‐analogous reactions of a poly(vinyl sugar) with a CC bond between sugar and polymer backbone

Abstract: The synthesis of a new type of poly(vinyl sugar) is described whose polymer backbone is connected with the monosaccharide unit by a C-C bond. Such polymers can be obtained by radical initiation. They show good stability in polymer-analogous reactions in contrast to common poly(vinyl saccharides) whose sugar residues are bound to the polymeric chain by ester, ether, or glycoside bonds. Starting from 7,8-dideoxy-1,2;3,4-di-O-isopropylidene-a-D-galacto-oct-7-en-1,5-pyranos-6-ulose (1) polymers (P1) could be obtained by emulsion polymerization in high yields. Reduction of the keto group of P1 proceeded quantitatively and yielded poly(7,8-dideoxy-1,2;3,4-di-O-isopropylidene-D,L-g1ycero-a-D-ga1acto-oct-7-en-l,5-pyranose) (P3). In contrast to the following polymers without protecting groups these poly(vinyl ketones), which were soluble in tetrahydrofuran and toluene, did not follow a pure GPC-separation mechanism. The protecting groups of the poly(vinyl saccharides), either with or without keto groups, could be removed completely to give P2 and P4. The solubility of the polymers P2 with galactose-functionalized side chains in water was limited to a weight-average molecular weight M ω of 1500000 due to association phenomena of the monosaccharide units. Reduction of the hemiacetal group and of the keto group of P2 yielded poly(1,2-dideoxy-D,L-glycero-D-galacto-oct- I -enitol) (P5) with sugar alcohol side chains instead of a cyclic monosaccharide unit. Oxidation of the hemiacetal group of P2 and P4 furnished poly(7,8-dideoxy-D-galacto-oct-7-en-6-ulosonic acid sodium salt) (P6) and poly(7,8-dideoxy-D,L-glycero-D-galacto-oct-7-enonic acid sodium salt) (P7), respectively. These polymers showed very high viscosities because of their polyelectrolyte character.