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Prebiotic sugar synthesis: hexose and hydroxy acid synthesis from glyceraldehyde catalyzed by iron(III) hydroxide oxide.

Iron(III) hydroxide oxide [Fe(OH)O] efficiently catalyzed the condensation of 25 mM DL-glyceraldehyde to ketohexoses at 25 degrees C (pH 5-6). At 16 days the yields were sorbose (15.2%), fructose (12.9%), psicose (6.1%), tagatose (5.6%), and dendroketose (2.5%) with 19.6% of triose unreacted. Analysis at 96 days showed no decomposition of hexoses. Under these conditions Fe(OH)O also catalyzed the isomerization and rearrangement of glyceraldehyde to dihydroxyacetone and lactic acid, respectively. In these reactions, about 10% of the glyceraldehyde was oxidized to glyceric acid with concurrent reduction of the iron(III) to iron(II). The partial reduction of Fe(OH)O did not noticeably reduce its ability to catalyze hexose synthesis. The relationship of these results to prebiotic sugar synthesis is discussed.

Carbohydrates↗

Dysinosin A: a novel inhibitor of Factor VIIa and thrombin from a new genus and species of Australian sponge of the family Dysideidae.

A new marine natural product dysinosin A 1 has been isolated from a new genus and species of sponge of the family Dysideidae found near Lizard Island, North Queensland, Australia. Dysinosin A is a potent inhibitor of the blood coagulation cascade factor VIIa and an inhibitor of the serine protease thrombin. Among the distinctive features of dysinosin A are the presence of a 5,6-dihydroxy-octahydroindole-2-carboxylic acid, 3-amino-ethyl 1-N-amidino-Delta-3-pyrroline, a sulfated glyceric acid, and d-leucine, assembled through three peptidic linkages. Dysinosin A inhibited factor VIIa at a Ki of 108 nM and thrombin at a Ki of 452 nM. The identification of the 1-N-amidino-Delta-3-pyrroline and 5,6-dihydroxy-octahydroindole-2-carboxylic acid as P1 and P2 moieties respectively, should pave the way for the design and synthesis of new structure-based inhibitors.

Animals↗

Glyoxylate metabolism in growth and sporulation of Bacillus cereus.

Megraw, Robert E. (Iowa State University, Ames), and Russell J. Beers. Glyoxylate metabolism in growth and sporulation of Bacillus cereus. J. Bacteriol. 87:1087-1093. 1964.-Isocitrate lyase and malate synthetase were found in cell-free extracts of Bacillus cereus T. The patterns of synthesis of enzymes of the glyoxylic acid cycle were dependent upon the medium in which the organism was grown. Cells grown in acetate or in an acetate precursor, such as glucose, produced enzymes of the glyoxylic acid cycle in greatly diminished quantities, as compared with cells grown in media containing glutamate or yeast extract as principal carbon sources. Glutamate-grown cells had high isocitrate lyase activity but very low malate synthetase activity. Glyoxylate produced in this situation is metabolized by alternate pathways: conversion to tartronic semialdehyde and the latter to glyceric acid, thus providing evidence for a glycerate pathway; and reduction to glycolate (the reverse of this reaction was present at a low rate). Enzymatic activity of the glyoxylic acid cycle declines at the point where sporogenesis begins, indicating a metabolic shift for the synthesis of spore material.

Acetates↗

Cyclic water pentamers in triclinic crystals of brucinium L-glycerate.

Brucinium L-glycerate 4.75-hydrate, C23H27N2O4+.C3H5O4-.4.75H2O, was obtained by racemic resolution of DL-glyceric acid. This is the first report of triclinic crystals containing brucine. The water and L-glycerate anions form tapes built up of pentamers formed by water and carboxy O atoms, and this appears to be the reason for the low symmetry of the crystal.

Journal Article↗

Glycolic acid in urine. A colorimetric method with values in normal adult controls and in patients with primary hyperoxaluria.

An improved Chromotropic acid-sulfuric acid assay for urinary glycolic acid is described. The sample (0.5 ml or less) is precleaned by filtering through strongly acidic and strongly basic ion-exchangers and compared with a standard made up in normal urine. From the many compounds tested, only glyceric acid in pathologically high concentrations interfers partially; this interference can be recognized at 776 nm and eliminated by a second determination. Per man-day, 8--12 samples can be analyzed. Recovery of 0.8 mmol/l glycolic acid added to the urines of 12 persons was 100.6 +/- 4.7% (1 S.D., n=12) without, and 101.9 +/- 5.3% (1 S.D., n=12) with correction for isotope dilution of [1-14C]glycolic acid, respectively, using 0.5-ml sample volumes. The variation coefficients of a single determination were 1.5 and 2.1% without and with correction for isotope dilution, respectively (n=7). The method was checked by mass fragmentography. The following normal values were found in adults (n=15; x +/- 1 S.D. (range)): 47.3 +/- 10.1 (24.4--63.7) mmol/mol creatinine and 0.60 +/- 0.15 (0.29--0.91) mmol/day or 45.8 +/- 11.3 (22.2--69.0) mg/day. Two patients (F.G. and A.S.) with primary hyperoxaluria type I excreted glycolic acid between 112 and 379 mmol/mol creatinine and 1.21--5.64 mmol/day or 92--429 mg/day. Under vitamin B-6 treatment, urinary excretion decreased in one patient (F.G.) to 71--131 mmol/mol creatinine and 0.92--2.0 mmol/day or 70--152 mg/day.

Adult↗

Quantification of sugars and organic acids in hygroscopic pharmaceutical herbal dry extracts.

Three chromatographic methods have been employed for the determination of hydrophilic compounds, namely carbohydrates and organic acids in herbal dry extracts of Eschscholtzia californica Cham. The hydrophilic compounds were separated from the other components of the dry extracts by solid-phase extraction methods, which were optimised with respect to recovery rates. Carbohydrates were quantified using high-performance anion-exchange chromatography with pulsed amperometric detection. Organic acids were analysed by ion-exclusion chromatography with evaporative light scattering detection and gas chromatography-mass spectrometry. Using the latter method, large amounts of glyceric acid were separated from the extracts of Eschscholtzia californica Cham. This substance together with sugars may be responsible for the increased hygroscopicity and the poor processing behaviour of the extracts.

Acids↗

Structural characteristics of endogenous sugar acids and relations to feeding modulation.

Structural specificity among short-chain organic acids for effects on feeding behavior, blood glucose and insulin was investigated by infusion of 1 exogenous and 6 endogenous derivatives into the rat third cerebral ventricle. Glyceric acid (GEA) (1.0 mumol), 3,4-dihydroxybutanoic acid gamma-lactone (3,4-DB) and 3,4,5-trihydroxypentanoic acid gamma-lactone (3,4,5-TP) (2.50 mumol) decreased food intake for, at most, 24 h. These acids depressed the size of the first meal after infusion, but did not affect latency to the first meal, eating speed, drinking or ambulation. Infusion of 2,4-dihydroxybutanoic acid gamma-lactone (2,4-DB) (1.25 mumol), 2,4,5-trihydroxypentanoic acid gamma-lactone (2,4,5-TP), and an exogenous compound, 2,4,5,6-tetrahydroxyhexanoic acid gamma-lactone (2,4,5,6-TH) (2.50 mumol), induced transient initial feeding which was not necessarily accompanied by periprandial drinking. Ambulation was concomitantly increased. Of these organic acids, 3,4-DB and 2,4,5-TP were most potent in their effects on feeding. Hyperglycemia was induced by 2.50 mumol 3,4-DB leaving insulin unaffected; 2.50 mumol 2,4,5-TP caused hypoglycemia, with a persistent but not significant rise in insulin. The results suggest that slight structural differences of endogenous organic acids, in particular the positions of hydroxyl groups on the lactone ring of 4-butanolide, may be important in feeding modulation by conveying intrinsically reciprocal signals to neurons involved in feeding and satiety.

Animals↗

Organic Acid Changes in the Epidermis of Vicia faba and Their Implication in Stomatal Movement.

Considerable evidence indicates that the increase in guard cell turgor resulting in stomatal opening is brought about by active K(+) uptake into guard cells. Only a small increase in inorganic anions appears to accompany the increase in K(+). A plausible explanation is that organic acids are produced within guard cells and act as counterions, whereas the H(+) produced are exchanged for K(+).This hypothesis was tested by using different levels of ambient CO(2) in light to control stomatal aperture and at the same time measure changes in organic acid production in the epidermis of Vicia faba. Epidermal strips were used, quickly frozen in liquid nitrogen, and later extracted.A positive correlation was found between stomatal resistance (r(s), indirect measure of stomatal aperture) and CO(2) level. With decreases in r(s), total titratable acidity increased. The organic acids, glyceric, malic, and citric, in the epidermis, as measured by gas chromatography of trimethylsilyl derivatives, increased. Changes in glucose or sucrose were not found. These analyses provided evidence that organic acid production in the epidermis is associated with stomatal opening.

Journal Article↗

Loss of Hydrogen from Carbon 5 of d-Glucose during Conversion of d-[5-H,6-C]Glucose to l-Ascorbic Acid in Pelargonium crispum (L.) L'Hér.

Conversion of d-[5-(3)H,6-(14)C]glucose to l-ascorbic acid in detached apices of Pelargonium crispum (L.) L'Hér cv Prince Rupert (lemon geranium) was accompanied by complete loss of tritium in the product. Chemical degradation of d-glucose which was recovered from the labeled apices yielded d-glyceric acid (corresponding to carbons 4, 5, and 6 of glucose) with a (3)H:(14)C ratio of 4 to be compared with 9, the ratio in d-[5-(3)H,6-(14)C]glucose initially. Conversion of d-[6-(3)H,6-(14)C]glucose in the same tissue was accompanied by retention of tritium in l-ascorbic acid with a (3)H:(14)C ratio comparable to that of compounds from the hexose pool. Results indicate that during l-ascorbic acid biosynthesis from glucose in Pelargonium crispum hydrogen at carbon 5 undergoes exchange with the medium, suggesting an epimerization at this carbon atom.

Journal Article↗

Hydroxycinnamic Acid Derivatives, Caffeoylmalic and New Caffeoylaldonic Acid Esters, from Chelidonium majus*,1.

HPLC analysis of a hydrolyzed extract obtained from the aerial parts of CHELIDONIUM MAJUS yielded 0.4% caffeic, 0.06% P-coumaric, and 0.02% ferulic acids; gentisic and P-hydroxybenzoic acids were below 0.01%. The caffeic acid derivatives occur as esters of which four were isolated using gel permeation chromatography, centrifugal partition chromatography and HPLC; they were assigned on the basis of their spectroscopic data ( (1)H-, (13)C-NMR, UV, MS) as the new (-)-2-( E)-caffeoyl- D-glyceric acid, (-)-4-( E)-caffeoyl- L-threonic acid, (-)-2-( E)-caffeoyl- L-threonic acid lactone, and the known (+)-( E)-caffeoyl- L-malic acid.

Journal Article↗

Structural studies of the enteroinvasive Escherichia coli (EIEC) O28 O-antigenic polysaccharide.

The structure of the O-specific side-chain of the lipopolysaccharide from Escherichia coli O28 has been investigated. NMR spectroscopy has been the main method used, complemented with sugar and methylation analyses. The polysaccharide contains one equivalent of O-acetyl groups per repeating unit. Selective cleavage of the O-deacetylated polymer was performed by treatment with aqueous hydrofluoric acid, and resulted in a trisaccharide-glycerol. The polysaccharide thus is of the teichoic acid type and composed of repeating units in which the trisaccharide-glycerol residues are joined by phosphodiester linkages. The O-antigen polysaccharide has the following structure. [sequence: see text] The absolute configuration of the glycerol moiety as R, )i.e., D-glycerol 1-phosphate) was determined by a new method based on TEMPO oxidation of the polysaccharide, followed by GLC analysis of the (+)-2-butyl ester of the resulting glyceric acid.

Carbohydrate Conformation↗

Synthesis of mono- and disaccharide analogs of moenomycin and lipid II for inhibition of transglycosylase activity of penicillin-binding protein 1b.

Three types of mono- and disaccharides 3a,b, 4a-c, 5, and some chaetomellic acid A analogs 6 and 42-44 were synthesized as potential inhibitors of the transglycosylase activity of penicillin-binding protein 1b (PBP1b), a key bacterial enzyme responsible for the formation of the polysaccharide backbone of peptidoglycan as well as for cross-linking of its peptide portions. The target compounds combine structural features of both the active portion of moenomycin and the natural PBP1b substrate, lipid II. The desired skeletons were obtained in a convergent fashion involving attachment of the lipid-alkylated glyceric acid moieties 11a,b to the corresponding carbohydrate-containing phosphonic acids 23, 24a, and 24b. Compounds 3a,b were prepared to verify the distance requirements between the sugar and the noncleavable C-phosphonate moieties. Compounds 4a-c were synthesized to examine the importance of the first sugar unit of moenomycin, a known inhibitor of transglycosylase catalysis by PBP1b, with respect to antibiotic activity. These were prepared by condensation of 11a,b with 28a and 28c, which were made by glycosylation of 3-bromopropanol with oxazolines 25a,b, and Arbuzov reaction with triethyl or trimethyl phosphite, followed by dealkylation with bromotrimethylsilane. Compound 5 was generated to verify the possibility of using a dicarboxylate group to mimic the diphosphate of lipid II. It was synthesized by coupling of alcohol 31 with alpha-trichloroacetimidate 34. Chaetomellic acid A analogs were prepared by a Michael addition to dimethyl acetylenedicarboxylate. With the exception of 3b, all of the target compounds were found to inhibit PBP1b, albeit with modest potency.

Bambermycins↗

Level of photosynthetic intermediates in isolated spinach chloroplasts.

The level of intermediates of the photosynthetic carbon cycle was measured in intact spinach chloroplasts in an attempt to determine the cause of the induction lag in CO(2) assimilation. In addition, transient changes in the level of the intermediates were determined as affected by a light-dark period and by the addition of an excess amount of bicarbonate during a period of steady photosynthesis. Assayed enzymically were: ribulose 1,5-diphosphate, pentose monophosphates (mixture of ribose 5-phosphate, ribulose 5-phosphate and xylulose 5-phosphate, hexose monophosphates (mixture of glucose 6-phosphate, glucose 1-phosphate, and fructose 6-phosphate), glyceraldehyde 3-phosphate, dihydroxyacetone phosphate, glycerate acid 3-phosphate, a mixture of fructose 1,6-diphosphate and sedoheptulose 1,7-diphosphate, adenosine triphosphate (ATP), adenosine diphosphate (ADP), and adenosine monophosphate (AMP).The lag in CO(2) fixation appeared to be the result of low levels of pentose monophosphates. The level of ribulose 1,5-diphosphate was roughly equal in chloroplasts showing immediate linear kinetics with respect to CO(2) fixation and chloroplasts which exhibited an initial lag.Following a light-dark transition, CO(2) fixation ceased immediately but the level of glycerate 3-phosphate increased while ribulose 1,5-diphosphate was only slightly effected. The increase in level of glycerate 3-phosphate was correlated with a decrease in triose phosphate. Within 3 to 5 min in the light, ATP reached a maximum concentration while in darkness, all was utilized in 30 to 60 sec. The rapid loss of ATP was ascribed to an ATPase rather than to its utilization in kinase reactions.A rapid increase in CO(2) concentration enhanced the level of triose phosphate, but the level of glycerate 3-phosphate showed only a small overshoot and was considered as evidence that reducing power was not a rate limiting factor. Data were obtained indicating that triose phosphates similar to pentose monophosphates and in contrast to fructose 6-phosphate, glucose 6-phosphate and glucose 1-phosphate could be transported between chloroplast and suspending medium. Differential import and export of phosphorylated compounds may serve as routes alternative to starch and sucrose for the flow of carbon into biosynthetic pathways.

Journal Article↗

Human red blood cells targeted metabolome analysis of glycolysis cycle metabolites by capillary electrophoresis using an indirect photometric detection method.

A capillary electrophoretic (CE) method with UV indirect spectrophotometric detection for determination of the main compounds of glycolysis in human erythrocytes has been elaborated. Blood samples for electrophoretic analysis were prepared by isolation of erythrocytes, lysis of the cells by heating in double-distilled water and subsequent ultrafiltration with a centrifuge equipped with filter devices: Mr cut off 5000. Using 20 mM 2,6-pyridinedicarboxylic acid (PDC) as a highly UV absorbing carrier electrolyte and 4 mM cetyltrimetylammonium bromide (CTAB), at the resulting pH 12.3, nine of the glycolysis intermediates were separated and characterized. The repeatability and linearity of the method was assessed with percent relative standard deviation (%R.S.D.) for migration time ranging from 0.3 to 1.9% and correlation coefficients of 0.991-0.999 for the studied concentration range. Limits of detection (LOD) for the analyzed metabolites were in the range of 6.25 x 10(-6) to 5.0 x 10(-5) M. The optimized CE method was used to compare metabolome content of red blood cells of 22 healthy volunteers. Mean metabolite concentrations in erythrocytes ranged from 49.6 microM for fructose-6-phosphate (F-6-P) to 3.1 mM for 2,3-diphospho-D-glyceric acid (2,3-DPG). The method can be readily applied in clinical, pathophysiological and epidemiological studies.

2,3-Diphosphoglycerate↗

Glyceraldehyde metabolism in human erythrocytes in comparison with that of glucose and dihydroxyacetone.

Metabolism of D-glyceraldehyde in human erythrocytes in comparison with that of glucose and dihydroxyacetone was studied. Both trioses were metabolized to produce L-lactate at rates comparable to that of L-lactate formation from glucose. Almost complete inactivation of glyceraldehyde-3-phosphate dehydrogenase by treatment of cells with iodoacetate resulted in a 95% decrease in L-lactate formation from the ketotriose as well as from glucose, whereas L-lactate formation from the aldotriose was only partially reduced (60%). D-Lactate was produced faster from either the aldotriose or the ketotriose than from glucose, but the ability of the two trioses to produce D-lactate was far lower than that to produce L-lactate. Almost complete inhibition of aldehyde dehydrogenase by disulfiram and of both aldose reductase and aldehyde reductase II by sorbinil, had no effect on L-lactate formation from D-glyceraldehyde. The present study suggests that D-glyceraldehyde is metabolized via two or more pathways including the glycolytic pathway after its phosphorylation by triokinase, and that neither oxidation to D-glyceric acid nor reduction to glycerol is a prerequisite for D-glyceraldehyde metabolism.

Carbohydrate Metabolism↗

Pyruvate kinase mutants of Saccharomyces cerevisiae: biochemical and genetic characterisation.

Mutants of Saccharomyces cerevisiae lacking pyruvate kinase (EC 2.7.1.40) are described. These have less than 0.5% of the pyruvate kinase activity of the wild type. All the other glycolytic enzymes are present in normal amounts in these mutants. The mutation is recessive and segregates in diploids as a single gene. Five alleles examined fail to complement one another. Tetrad analysis and mitotic recombination data place the mutation on the left arm of chromosome I distal to cys 1. The majority of single-step spontaneous revertants on glucose regain the enzyme activity fully and this activity appears, by a number of criteria, to be due to the same enzyme present in the wild type. Some of these revertants become nuclear petites. The mutants do neither grow on nor ferment sugars but do grow on ethyl alcohol or pyruvate. Glucose addition to cultures growing on alcohol arrests growth until glucose is exhausted. The steady state rate of glucose utilization is slower than in the wild type. This is associated with the accumulation of as much as 5 micronmoles P-enolpyruvate per g wet weight of cells and proportional amounts of 2-P-glyceric and 3-P glyceric acids. The mutation is believed to involve some regulatory element in the synthesis of pyruvate kinase.

Chromosome Mapping↗

A comparison of the degradation products formed in aerated, aqueous alpha-D-glucose solutions by ultrasound and gamma rays.

The degradation products formed in aerated aqueous alpha-D-glucose solutions by cleavage of the carbon skeleton by ultrasound and gamma irradiation are compared. Common products present for both types of irradiation are: D-glyceraldehyde, D-glyceric acid, hydroxy-malondialdehyde, 2,3-dihydroxy-4-oxo-butanoic acid, tetrodialdose, D-arabinoic acid and D-xylose. 2,3,4-Trihydroxy-5-oxo-pentoic acid and D-arabinose could be detected only by radiolysis and evidence for the formation of 2-hydroxy-3-oxo-pentoic acid was only obtained in sonolysis. These fragmentation products are supposed to be formed by reactions of the glucose-peroxyl radicals with HO2-radicals. Based on the reactions of peroxyl radicals given in the literature, a mechanism is proposed which leads to the observed products.

Chemical Phenomena↗

The inhibition of insulin secretion from the perfused rat pancreas after thyroxine treatment.

Thyroxine treatment did not significantly affect the immediate insulin secretory response of the perfused rat pancreas, but it inhibited the late phase of D-glucose-induced insulin secretion. Thyroxine treatment did not inhibit D-glyceraldehyde-, D-mannose-, and tolbutamide-induced insulin release from the perfused pancreas. An increase in the D-glucose concentration of the perfusion medium as well as feeding of the rats did not restore insulin secretion after thyroxine treatment. The inhibition of D-glucose-induced insulin release in response to thyroxine treatment was reversed after addition of either D-glyceraldehyde, dihydroxyacetone, DL-glyceric acid, pyruvate, or alpha-ketobutyrate to the perfusion medium. Tolbutamide, L-glucose, D-fructose, D-mannose, L-lactate, and propionic acid were not able to overcome the inhibition of D-glucose-induced insulin secretion. Except for alpha-ketobutyrate all substances which were effective in reversing the inhibition of D-glucose-induced insulin release were glycolytic intermediates. Comparing the glycolytic alpha-ketoacid pyruvate and the non-glycolytic ketoacid alpha-ketobutyrate, the only part common to both substances was the ketoacid moiety. It is concluded from these findings that the ketoacid moiety of the alpha-ketoacids plays an important role in reversing the effect of thyroxine on D-glucose-induced insulin release.

Animals↗