PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Tetroses”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1979

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

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 1.7 +/- 0.1 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.

Carbohydrate Epimerases↗
PubMed2006

The peptide-catalyzed stereospecific synthesis of tetroses: a possible model for prebiotic molecular evolution.

Using a water-based prebiotic model of sugar synthesis involving glycolaldehyde self-condensation, we demonstrate that homochiral L-dipeptide catalysts lead to the stereospecific syntheses of tetroses. The asymmetric effect is largest for erythrose, which may reach a D-enantiomeric excess of >80% with L-Val-L-Val catalyst. Based on results obtained with various peptides, we propose a possible catalytic-reaction intermediate, consisting of an imidazolidinone ring formed between the two nitrogen atoms of the peptide catalyst and the C1 of one glycolaldehyde molecule. The study was motivated by the premise that exogenous material, such as the nonracemic amino acids found in meteorites, could have participated in the terrestrial evolution of molecular asymmetry by stereospecific catalysis. Because peptides might have formed readily on the early Earth, it is possible that their catalytic contribution was relevant in the prebiotic processes that preceded the onset of life.

Catalysis↗
PubMed1975

Studies on D-tetrose metabolism. VI. Crystallization and some properties of D-erythrulose reducatase from beef liver.

D-Erythrulose reductase of beef liver was crystallized from ammonium sulfate solution at pH 8.17. The crystals are needle-shaped. The enzyme protein contains 851 amino acid residues per mole of the enzyme: Lys28, His11, Arg52, Asp79, Thr58, Ser56, Glu68, Pro20, Gly80, Ala107, Val112, Met24, Ile31, Leu88, Tyr7, Phe22, Trp4, and Cys4. The enzyme is inactivated by exposure to temperatures below 12degrees. The inactivation is accelerated by increasing the salt concentration and decreasing the enzyme concentration. The pH of the medium also has a pronounced effect, the maximum stability of the enzyme is obtained at pH 8.5. NADP+ protected the enzyme from cold inactivation at all stages of the process and also afforded protection against inactivation by heat and pH. The cold inactivation of the enzyme is accompanied by dissociation of the enzyme protein to subunits.

Alcohol Oxidoreductases↗
PubMed1980

Studies on D-tetrose metabolism. Crystallization and properties of D-erythrulose reductase from chicken liver.

D-Erythrulose reductase from chicken liver has been purified to homogeneity as judged by acrylamide gel electrophoresis and ultracentrifugation. The overall purification of the enzyme was 164-fold from a crude extract. The enzyme was crystallized from ammonium sulfate solution at pH 7.0 to give hexagonal plates. The molecular weight determined by sedimentation equilibrium analysis was 94,600 and that by SDS-polyacrylamide gel electrophoresis was 22,400, which suggests a tetrameric structure for the native enzyme. The enzyme was found to contain up to 3 molecules of NADP+ per enzyme; this high amount of NADP+ resulted in a higher absorption at 260 nm than at 280 nm. The extinction coefficient of the enzyme at 290 nm was found to be 4.0. The contents of various amino acids were very similar to those of the beef liver enzyme formerly crystallized in our laboratory. The isoelectric point of the enzyme determined by Ampholine isoelectric focusing was pH 6.43. The enzyme was shown to catalyze the reduction of D-erythrulose to D-threitol with the concomitant oxidation of NAD(P)H to NAD(P)+, and was highly specific to D-erythrulose with an apparent Km of 0.38 mM. NADH was less effective than NADPH and the Km's for NADH and NADPH were 67 micrometers and 7.9 micrometers, respectively. D-Threitol was slightly oxidized by the enzyme with either NADP+ or NAD+ as a cofactor at pH's 7.5 and 9.0.

Amino Acids↗
PubMed1997

[Inhibitory effects of two oligosaccharides on murine melanoma experimental metastasis].

OBJECTIVE: To observe the effects of a chemically synthesized tetrose and a natural yeast mannan on mouse melanoma experimental liver metastasis. METHODS: After treated with 4 mg tetrose (tetrose group) or 4 mg mannan (mannan group) for 30 minutes at 37 degrees C, 0.5 ml 1 x 10(6)B16-MBK melanoma cells were injected intraspleen. 55 days later, melanoma metastasis nodes in the surfaces of the liver and other organs as well as mouse survival time were observed. RESULTS: Of 6 mice in control (B16 cell+PBS), 4 died naturally within 55 days, 2 were dissected in the 55th day. All of the 6 mice had metastases in the livers, the total number of the melanoma nodes on each liver surface ranged from 2 to 30, with the largest one fused to the whole liver. One mouse had a neoplasm in the remnant site of injection, 3 had metastases in lungs, while of the 6 mice in the tetrose group, one died on the 50th day on injection. In mannan group, all of the 6 mice survived and no metastasis was seen except the largest diameter of < 1 mm of 2 liver nodes in one mouse. Neither tetrose nor mannan group had metastasis of the liver, and the weights of liver in the two groups were significantly lower than in the control. CONCLUSION: Both tetrose and mannan had the effects in blocking melanoma experimental liver metastasis, inhibiting transmigration of the liver, and prolonging the survival time of the mouse.

Animals↗
PubMed1998

Inhibitory effects of two oligosaccharides on murine melanoma experimental liver metastasis.

AIM:To observe the effects of a chemically synthesized tetrose and a natural yeast mannan on experimental liver metastasis of mouse melanoma.METHODS: After treated with 4mg tetrose (tetrose group) or 4mg mannan (mannan group) for 30 minutes at 37&mgr;,0.5ml 1 10(6) B16-MBK melanoma cells were injected into the spleen of mice.Fifty-five days later, melanoma metastatic nodes on the surface of the liver and in other organs as well as mouse survival time were observed.RESULTS: Of the 6 mice in control (B16 cell+PBS) group, 4 died naturally within 55 days, and 2 were killed on the 55th day.All of the 6 mice had metastases in livers, the total number of the melanoma nodes on each liver surface ranged from 2 to 30, with the largest one merging into the whole liver. One mouse had a neoplasm in the remnant site of injection, and 3 had metastases in lungs.In contrast, of the 6 mice in tetrose group, only one died on the 50th day after injection, with 3 metastases in the liver, the largest being 10mm in diameter, the other 5 mice survived until being dissected on the 55th day after injection and had no liver metastasis,but 3 of them had neoplasms in their remnant sites of injection.In mannan group,all of the 6 mice survived and no metastasis was seen except for 2 liver nodes in one mouse with the largest diameter of 1mm.Neither tetrose nor mannan group had metastasis out of the liver, and the weight of liver in the two groups was significantly lower than those in the control group.CONCLUSION:Both tetrose and mannan had the effects of preventing melanoma cells from experimental metastasis to and out of the liver, and prolonging the survival time of the mouse.

Journal Article↗