The crystal structure of di-D-fructose anhydride III,produced by inulin D-fructotransferase

Reaction of methyl α-d-glucopyranoside and methyl α-d-mannopyranoside with alkaline hydrogen peroxide and a ferrous salt, at room temperature and below, afforded the corresponding d-glycosiduronic acids. On dehydration, the acids gave the corresponding gamma lactones, with a shift of the pyranoid ring to a furanoid ring. Surprisingly, the glycosidic methyl group was retained during the oxidation reactions and pyranose-furanose interconversions. This retention is rationalized by a mechanism involving formation of a pseudo-acyclic intermediate. Another unexpected reaction was the conversion of slightly moist methyl d-glucopyranosiduronolactone syrup, on standing for 5–6 days at room temperature, into crystalline d-glucofuranurono-6,3-lactone, and of methyl α-d-mannopyranosidurono-6,3-lactone into crystalline d-mannofuranurono-6,3-lactone.     

Recent advances on biological difructose anhydride III production using inulase II from inulin

Difructose anhydride III (DFA III), the smallest cyclic disaccharide, consists of two fructose residues. DFA III is a hydrolysate of inulin and is rarely found in nature. Industrial interest in DFA III as a low-calorie sugar substitute is increasing. The present review describes the properties and physiological functions of DFA III as well as its commercial importance. Focus is also given on the biological production of DFA III from inulin, which contains enzyme resources, inulase II properties, and the capacity for mass DFA III production. Inulase II as an industrial enzyme and its molecular evolution are discussed as well. The aim is to better understand commercial-scale DFA III production as a food product.     

Effects of inulin and di-d-fructose dianhydride-enriched caramels on intestinal microbiota composition and performance of broiler chickens

In vitro and in vivo experiments were designed to evaluate the effectiveness of laboratory-made di-d-fructose dianhydride (DFA)-enriched caramels. The DFA-enriched caramels were obtained from d-fructose (FC), d-fructose and sucrose (FSC), or d-fructose and β-cyclodextrin (FCDC). In the in vitro experiment, raftilose and all caramels increased (P<0.05) l-lactate concentration and decreased (P<0.05) pH. Total short-chain fatty acid concentration was higher (P<0.05) than controls in tubes containing raftilose, FSC, FCDC and commercial sucrose caramel (CSC). Raftilose, and all caramels tested except FSC and FC (1%), increased (P<0.01) lactobacilli log₁₀ number of copies compared with the non-additive control. FSC, FCDC and CSC increased (P<0.01) the bifidobacteria number of copies as compared with controls. All additives, except FCDC, decreased (P<0.01) Clostridium coccoides/Eubacterium rectale log number of copies. Compared with controls, raftilose, FC and CSC led to lower (P<0.01) Escherichia–Shigella and enterobacteria. For the in vivo experiment, a total of 144 male 1-day-old broiler chickens of the Cobb strain were randomly assigned to one of the three dietary treatments for 21 days. Dietary treatments were control (commercial diet with no additive), inulin (20 g inulin/kg diet) and FC (20 g FC/kg diet). Final BW of birds fed FC diet was higher (P<0.01) than controls or inulin-fed birds, although feed: gain values were not different. Feed intake of chickens fed FC was higher (P<0.01) than that of inulin-fed birds but not statistically different from controls. Crop pH values were lower (P<0.01) in birds fed FC diet as compared with control diet, with inulin-fed chickens showing values not different from control- or FC-fed birds. Lower (P<0.05) lactobacilli number of copies was determined in the crop, ileum and caeca of birds fed the inulin diet compared with the control diet. Inulin supplementation also resulted in lower (P<0.05) C. coccoides/E. rectale, bacteroides and total bacteria in caecal contents. Addition of FC to broiler diets gave place to lower (P<0.05) enterobacteria and Escherichia–Shigella in crop and caecal contents compared with controls. The bacteroides number of copies increased (P<0.05) as compared with controls in the ileum, but decreased (P<0.05) in the caeca of chickens fed the FC diet. Energy, ADF, NDF and non-starch polysaccharides faecal digestibilities were greater (P<0.05) than controls in chickens fed diets containing inulin or FC. Fat digestibility was higher (P<0.05) in FC-fed birds compared with controls or inulin-fed chickens. In conclusion, DFA-enriched caramels tested here, particularly FC, may represent a type of new additives useful in poultry production.     

Anomeric specificity of mannose phosphorylation by hexokinase

In rat parotid or pancreatic islet homogenates incubated at 7 degrees C, hexokinase displayed a greater affinity for but a lower maximal velocity with the alpha-anomer, as distinct from beta-anomer, of D-mannose. The anomeric specificity of mammalian hexokinase was similar in the case of D-mannose and D-glucose, but represented a mirror image of that of yeast hexokinase.     

Anomeric specificity of D-glucose production by rat hepatocytes

The anomeric specificity of D-glucose metabolism in intact hepatocytes remains a matter of debate. This issue was further investigated in the present study, which is based on the quantification of the alpha- and beta-anomers of the 13C-enriched isotopomers of D-glucose generated by rat liver cells exposed to either D-[1-13C] fructose or D-[2-13C] fructose in the presence of D2O. The D-[1-13C]glucose/D-[6-13C]glucose paired ratios found in the cells exposed to D-[1-13C] fructose and the D-[2-13C]glucose/D-[5-13C]glucose paired ratios found in the cells exposed to D-[2-13C] fructose yielded a paired beta/alpha ratio averaging (mean +/- S.E.M.) 79.3 +/- 6.1%. In the case of the isotopomers of D-glucose formed by gluconeogenesis, the D-[2-13C]glucose/D-[5-13C]glucose and D-[3-13C]glucose/D-[4-13C]glucose paired ratios found in cells exposed to D-[1-13C] fructose, as well as the D-[1-13C]glucose/D-[6-13C]glucose and D-[3-13C]glucose/D-[4-13C]glucose paired ratios found in cells exposed to D-[2-13C]fructose, yielded an alpha/beta paired ratio averaging 75.0 +/- 5.8%. Last, in the cells exposed to D-[2-13C]fructose, the beta/alpha ratio for the C2-deuterated isotopomers of D-[2-13C]glucose represented 78.9 +/- 3.7% of that for the C5-deuterated isotopomers of D-[5-13C]glucose. The three values representative of the anomeric specificity of D-glucose production by liver cells were not significantly different from one another, with an overall mean value of 76.9 +/- 3.6%. These findings unambiguously document that the anomeric specificity of phosphoglucoisomerase is operative in intact hepatocytes, resulting in a preferential output of the alpha-anomer of 13C-enriched D-glucose under the present experimental conditions.     

Subsite mapping of purified glucoamylase I, II, III produced by Arthrobotrys amerospora ATCC 34468

Arthrobotrys amerospora ATCC 34468 produced glucoamylase in a medium containing maize starch as carbon source. On native PAGE, crude glucoamylase showed three isoenzymes which were designated as Glu I, Glu II, Glu III according to their electrophoretic mobility. These were purified by column chromatography techniques. The energy of binding for each glucoamylase was calculated using Hiromi's kinetic based calculation. At subsite 1, the binding energies for Glu I, II and III were found to be negative.     

Properties of zinc uroporphyrin III produced from isopropanol by Arthrobacter hyalinus

In a large amount of porphyrins produced by a bacterium isolated from soil, Arthrobacter hyalinus, cultured in a medium containing isopropanol as the sole carbon source, zinc porphyrins, identified based on the coincidence between their m/z values in LC/MS and the molecular weight of porphyrins, were also found to be produced. Since zinc is easily separated from porphyrins in acid during the esterification of porphyrins, zinc uroporphyrin III was prepared from its octamethyl ester formed by incorporating zinc into the octamethyl ester of uroporphyrin III which was isolated from the culture broth. Its UV spectra, fluorometric spectra, fast atom bombardment (FAB)-mass spectra, and ¹H-NMR and ¹³C-NMR spectra were presented.     

Effect of difructose anhydride III on calcium absorption in humans

The effects of difructose anhydride III (DFAIII) on stimulating calcium absorption was investigated in humans. We studied changes in the time-course of characteristics urinary calcium excretion in 12 healthy men given 0.3, 1.0 or 3.0 g of DFAIII and 300 mg of calcium as calcium carbonate. In addition, urinary excretion and urine concentrations of creatinine and deoxypyridinoline were determined. Urine calcium excretion every 2 hours after the intake were higher over than that of the control subjects. The total amount of urinary calcium excretion for 10 hours was significantly greates in the subjects given 1.0 g or 3.0 g of DFAIII than that of the control subjects. However, there were no differences in the urine concentrations of creatinine and deoxypyridinoline between the subjects given DFAIII and the control subjects. These findings suggests that low dose of DFAIII had a stimulating effect on calcium absorption in humans.     

Unambiguous Assignment of Anomeric Configuration of Nucleosides by Noe-Difference Spectroscopy

Abstract

An unambiguous assignment of anomeric configuration of D-ribo-, 2′-deoxy-D-ribo-, D-arabino and 2′,3′-dideoxy-D-ribonucleosides based on nuclear Overhauser enhancement spectroscopy is presented.     

Reversible inhibition of the mitochondrial ubiquinol-cytochrome c oxidoreductase complex (complex III) by ethoxyformic anhydride

The mitochondrial ubiquinol-cytochrome c oxidoreductase (complex III) is inhibited by ethoxyformic anhydride (EFA). The inhibition is readily reversed by hydroxylamine, suggesting the involvement of essential histidyl or possibly tyrosyl residues. The spectrum of ethoxyformylated complex III in the UV region showed a peak at 238 nm, indicative of N-(ethoxyformyl)histidine. Addition of hydroxylamine caused a large decrease of the 238-nm peak, which amounted to 16 mol of (ethoxyformyl)histidine/mol of cytochrome c1. Hydroxylamine addition to ethoxyformylated complex III also caused a small change at about 280 nm, which could be due to reversal of 1.6 O-ethoxyformylated tyrosyl residues/mol of cytochrome c1. Among many inhibitors of the cytochrome bc1 region of the respiratory chain, EFA is the only reagent known to cause reversible inhibition by covalent modification of amino acid residues. The inhibition site of EFA was determined to be between cytochromes b-562 and c1. However, unlike antimycin, which also inhibits in the same region, EFA did not promote the reduction of cytochrome b-566 in particles treated with substrates. In addition, it was found that EFA inhibits proton translocation in the cytochrome bc1 region and is a more effective electron transport inhibitor when added to reduced particles as compared to oxidized particles. These results together with the strong possibility that the EFA target is a histidyl or possibly a tyrosyl residue have been discussed in relation to the mechanism of proton translocation by complex III.     

Facilitated synthesis of inulin esters by transesterification

Inulin, the polydisperse polyfructose, extracted from chicory, has been modified via transesterification, using fatty acid methyl esters (FAME). The grafting of an alkyl chain onto the inulin backbone under different conditions for the development of potential tensio-active derivatives is described. The modification of the biopolymer was performed in polar organic solvents, such as dimethyl sulfoxide (DMSO) and N-methylpyrrolidinone (NMP). Depending on the type of solvent, different catalytic systems, such as DMSO-Na+, NaH, and NaOMe, were used and compared in reaction efficiency and reproducibility. Therefore the synthesized derivatives were characterized by 1H- and 13C NMR. The methods using NaH had a mean reaction efficiency of 80%, whereas the one using NaOMe showed a slight decrease in reaction efficiency to 75%. However, the method using NaOMe in NMP proved to be the preferred way to graft the inulin backbone with FAME on a bigger scale. The methods using DMSO as a solvent were not attractive since the end products had a specific bad smell.     

Quantitative determination of anomeric forms of sugar produced by amylases. V. Anomeric forms of maltose produced in the hydrolytic reaction of substituted phenyl alpha-maltosides catalyzed by saccharifying alpha-amylase from B. subtilis.

1. Hydrolyses of phenyl alpha-maltoside and its derivatives with various substituents (p-NO2, p-C1, p-CH3, p-C2H5, and p-C(CH3)3) catalyzed by saccharifying alpha-amylase from B. subtilis3 [EC 3.2.1.1] were studied under conditions such that the products were only maltose and the corresponding phenols (1), in order to determine quantitatively the anomeric form of the sugar produced from each substrate. 2. At the optimum pH of this enzyme (pH-5.4), maltose released from all the substituted substrates studied was entirely in the beta-form. These results are in remarkable contrast to the previous finding that alpha-maltose is exclusively produced from unsubstituted phenyl alpha-maltoside by this enzyme (2). 3. At pH 6.18 and 6.73, maltose produced from unsubstituted phenyl alpha-maltoside (?M) or p-tert-butylphenyl alpha-maltoside (PTB?M) was a mixture of alpha- and beta-anomers, the ratio being dependent on pH as follows: For ?M, the percentage of alpha-anomer was 100% (pH 5.4), 80 (pH 6.18), and 55% (pH 6.73), whereas for PTB?M, the percentage of beta-anomer was 100% (pH 5.4), 75% (pH 6.18), and 60% (pH 6.73).     

Pyrolysis of inulin,glucose and fructose

The pyrolytic behavior of inulin, a (2 → 1)-linked fructofuranan, is described. Parallel investigations of the pyrolysis of glucose and of fructose were conducted to supplement the inulin results and to aid comparison with previous results from glucans. Effects of neutral and basic additives are emphasized. As with glucans, the addition of such additives (especially basic) increases the yields of the one-, two-, and three-carbon products (as well as of hexosaccharinolactones), while generally decreasing the yields of anhydro sugar and furan derivatives. The former products include glycoaldehyde, acetol, dihydroxyacetone, acetic acid, formic acid, and lactic acid. Mechanistic speculations are made regarding the origins of these compounds, as well as of furan derivatives and saccharinic acid lactones. Parallels with alkaline degradation are considered.