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.

Purification and Immunologic Identification of Aldose Reductases

Abstract: A general method for the identification and purification of aldose reductase (alditohNADP oxidoreductase, EC 1.1.1.21) and NADP-L-hexonate dehydrogenase (L-gulonate:NADP oxidoreductase, EC 1.1.1.19) from tissues is described. Two aldose reductase isoenzymes, AR-A and AR-B, were isolated from renal papilla and were characterized. These two forms were also found in brain, retina, pancreas, lens and optic nerve. AR-A and AR-B differed primarily in glucuronate-reducing activity. All tissues, with the exception of lens and optic nerve, also contained NADP-L-hexonate dehydrogenase activity. Human red blood cells contained NADP-L-hexonate dehydrogenase activity but not aldose reductase. The aldose reductases and the two isoenzyme forms isolated from these tissues were immunologically identical as demonstrated with a specific antiserum prepared in rabbits against papillary AR-B. The antiserum inhibited AR-A and AR-B activity equally in vitro. The extent of enzyme inhibition by the antiserum was similar when glucuronate, glucuronolactone, xylose and glyceraldehyde were used as substrates. The antiserum did not react with NADP-L-hexonate dehydrogenase. Therefore, the method provides a specific means for identifying aldose reductase in crude tissue homogenates.

Crystal structure of the reduced Schiff-base intermediate complex of transaldolase B from Escherichia coli: mechanistic implications for class I aldolases.

Abstract: Transaldolase catalyzes transfer of a dihydroxyacetone moiety from a ketose donor to an aldose acceptor. During catalysis, a Schiff-base intermediate between dihydroxyacetone and the epsilon-amino group of a lysine residue at the active site of the enzyme is formed. This Schiff-base intermediate has been trapped by reduction with potassium borohydride, and the crystal structure of this complex has been determined at 2.2 A resolution. The overall structures of the complex and the native enzyme are very similar; formation of the intermediate induces no large conformational changes. The dihydroxyacetone moiety is covalently linked to the side chain of Lys 132 at the active site of the enzyme. The Cl hydroxyl group of the dihydroxyacetone moiety forms hydrogen bonds to the side chains of residues Asn 154 and Ser 176. The C3 hydroxyl group interacts with the side chain of Asp 17 and Asn 35. Based on the crystal structure of this complex a reaction mechanism for transaldolase is proposed.

Carbon-13-enriched carbohydrates: preparation of triose, tetrose, and pentose phosphates

Abstract: Three-, four-, and five-carbon aldononitrile phosphates were prepared, purified, and catalyticlly reduced with palladium--barium sulfate (5%) to the corresponding aldose phosphates in high yields at pH 17 +/- 01 and atmopsheric pressure DL-Glyceraldehyde 3-phosphate and the tetrose 4-phosphates were prepared with carbon-13 enrichment at C-1, while the pentose 5-phosphates were prepared with enrichment at C-1 and C-2 Preparations of glycolaldehyde phosphate and d-glyceraldehyde 3-phosphate by lead tetra-acetate oxidation of glycerol phosphate and fructose 6-phosphate, respectively, are described The proportions of cyclic hemiacetals and linear gem-diol forms of the two- to five-carbon aldose phosphates in aqueous solution are reported Carbon-13 chemical shifts and carbon--phosphorus and carbon--hydrogen coupling constants for the furanose phosphate ring and linear gem-diol phosphates are reported and discussed d-[2(-13)C]Ribulose 1,5-bisphosphate and L-[3,4(-13)C]sorbose 1,6-bisphosphate were prepared enzymatically from D-[2(-13)C]ribose 5-phosphate and dl-[1(-13)C]glyceraldehyde 3-phosphate, respectively