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Publications (59)
Fusarium graminearum was grown on four lignocellulosic substrates (corn cobs, wheat bran, hop cell walls, and birchwood) and glucose as the sole carbon source. Proteomic studies performed on the resulting enzymatic cocktails highlighted a great diversity in the number and type of proteins secreted. The cell wall degrading enzymes (CWDE) proportion...
A purified feruloyl esterase (EC 3.1.1.73) from Aspergillus nidulans produced in Pichia pastoris was used to study the de-esterification of large feruloyl oligosaccharides consisting of 4 to 20 pentose residues and (xylose plus arabinose) and one ferulic acid residue. The feruloyl oligosaccharides were prepared from total oligosaccharidic hydrolysa...
This study was focused on investigating the role of the initial residue community, i.e. microorganisms and enzymes from the epiphytic and endophytic compartments, in soil decomposition processes. Aerial and underground parts (leaves and roots) of maize (Zea mays L.) plants were γ-irradiated, surface-sterilized with sodium hypochlorite (NaOCl)/ethan...
The resilient of Methanothrix soehngenii strain FE was isolated. It contained carbohydrates (7%), mainly rhamnose, ribose, and fucose, which could be specifically liberated by alkaline hydrolysis or hydrazinolysis. Four oligosaccharide-containing fractions were separated; the two major fractions corresponded to large glycans composed of 15–30 resid...
Soaking in aqueous ammonia (SSA) and/or xylanase pretreatments were developed on wheat straw. Both pretreatments were conducted at high-solids conditions: 15% and 20%, respectively, for SSA and xylanase pretreatments. SSA pretreatment led to the solubilisation of 38%, 12% and 11% of acid insoluble lignin, xylan and glucan, respectively. In case of...
The external envelope of wheat grain (Triticum aestivum L. cv. Isengrain) is a natural composite whose tissular and cellular heterogeneity constitute a significant barrier for enzymatic cell wall disassembly. To better understand the way in which the cell wall network and tissular organization hamper enzyme penetration, we have devised a strategy b...
Incubation of whole lymphocytes with UDP-N-acetyl [3H]glucosamine used as the only preeursor leads to the formation of dolichyl diphosphate [3H]chitobiose, DolPP-(GlcNAc)2, and dolichyl diphosphate N-acetyl- [3H]glucosamine, DolPP-GlcNAc. Although very few dolichyl diphosphate oligosaccharidcs are formed, a high level of radioactivity is recovered...
The external envelope of wheat grain (Triticum aestivum L. cv. Isengrain) is a natural composite whose tissular and cellular heterogeneity constitute a significant barrier for enzymatic cell wall disassembly. To better understand the way in which the cell wall network and tissular organization hamper enzyme penetration, we have devised a strategy b...
Hydroxycinnamate and protein contents and monosaccharide composition were determined for 11 industrial wheat (Triticum aestivum) brans and related to the susceptibility of their arabinoxylans (AX) to enzymatic degradation. There was significant variation in carbohydrate, A/X ratio, protein, hydroxycinnamic acid and diferulic acid (DiFA) content amo...
The results of a comparative study of two thermostable (1-->4)-beta-xylan endoxylanases using a multi-technical approach indicate that a GH11 xylanase is more useful than a GH10 xylanase for the upgrading of wheat bran into soluble oligosaccharides. Both enzymes liberated complex mixtures of xylooligosaccharides. 13C NMR analysis provided evidence...
Previous work has shown that (1→4)-β-D-endoxylanase-mediated hydrolysis of wheat bran leads to solubilization of 50% of arabinoxylans. However, xylanase efficiency on the individual bran tissues is unequal because of histological and chemical heterogeneity. We describe here the results of an immunocytochemical study that is aimed at an understandin...
Thermal treatment is one of the widely used methods for feedstuff preservation. The aim of this study was to evaluate possible cell wall alterations during the industrial‐scale drying of alfalfa. Alfalfa is mainly dehydrated and pelleted using two drying treatments. First a thermal treatment at 70 °C is applied to the chopped raw material, prior to...
A purified thermostable (1→4)-β-endo-xylanase, solubilised 50% of the arabinoxylan in cell walls of wheat bran. The monosaccharide composition of the hydrolysis products suggest that the xylanase solubilised only arabinoxylans with a high xylose/arabinose ratio, i.e. low substitution. In addition to the release of oligosaccharides, the endoxylanase...
The effects of heat treatments used to dry alfalfa stems were investigated. Heating at 70 or 100 degrees C caused no major change in the cell wall composition, but xylanase had lower activity on the cell wall of heated material and the amount of xylose released varied with the temperature used. Chemical fractionation of cell wall carbohydrates show...
The α-l-arabinofuranosidase D3 from Thermobacillus xylanilyticus is an arabinoxylan-debranching enzyme which belongs to family 51 of the glycosyl hydrolase classification. Previous studies
have indicated that members of this family are retaining enzymes and may form part of the 4/7 superfamily of glycosyl hydrolases.
To investigate the active site...
of the cat-alytic domain of an archaeal family 57 pullulanase type II. Biologia, Bratisla-va, 57/Suppl. 11: 155—162, 2002; ISSN 0006-3088. The catalytic domain (Apu∆2) of the thermostable family 57 pullulanase type II from the archaeabacterium Thermococcus hydrothermalis has been cloned. The activity of Apu∆2 in the presence of various reagents has...
A pullulanase type II was produced in Escherichia coli using the relevant gene from Thermococcus hydrothermalis. This protein was purified and its pullulanolytic and amylolytic activities were characterised. The optimum temperature and Ca2+ concentration for each activity were identical (105 C and 0.09 mM), whereas the optimum pH (pHpullulan 5.75,...
The gene encoding an α-l-arabinofuranosidase fromThermobacillus xylanilyticus D3, AbfD3, was isolated. Characterization of the purified recombinant α-l-arabinofuranosidase produced in Escherichia coli revealed that it is highly stable with respect to both temperature (up to 90°C) and pH (stable in the pH range 4 to 12).
On the basis of amino acid s...
An aerobic, thermophilic, xylanolytic, spore-forming bacterium, XETP (T = type strain; P = patent strain), has been isolated from farm soil situated underneath a manure heap in northern France. Strain XETP, which stained negative in the Gram test, occurs as short rods which sometimes form chains. Its spores are ellipsoidal, central to subterminal a...
A clone expressing xylanase activity in Escherichia coli has been selected from a genomic plasmid library of the thermophilic Bacillus strain D3. Subcloning from the 9-kb insert located the xylanase activity to a 2.7-kb HindII/BamHI fragment. The DNA sequence of this clone revealed an ORF of 367 codons encoding a single domain type-F or family 10 e...
Variants of the HSQC and HMBC experiments are described. They allow the restriction of the heteronuclear chemical shift domain without causing spectral folding. Selectivity is introduced in the HSQC experiment by means of excitation sculpting. The selective element of the pulse sequence is a double pulsed field gradient spin echo. It may be used ei...
Hydrolysis of wheat bran and wheat straw by a 20.7 kDa thermostable endoxylanase released 35 and 18% of the cell-wall xylan content, respectively. Separation of the cinnamoyl-oligosaccharides (accounting for 6%) from the bulk of total oligosaccharides was achieved by specific anion-exchange chromatography. The cinnamoyl-oligosaccharides were furthe...
The gene encoding a hyperthermostable type II pullulanase produced by Thermococcus hydrothermalis (Th-Apu) has been isolated. Analysis of a total of 5.2 kb of genomic DNA has revealed the presence of three open reading frames, one of which (apuA) encodes the pullulanase. This enzyme is composed of 1,339 amino acid residues and exhibits a multidomai...
Oxidants formed through the interaction between MnO2 and oxalate accumulated in rotten wood have been evaluated as abiotic agents possibly involved in wheat straw ligninolysis. The hemicellulose and cellulose content of straw remained unchanged, and no release of free soluble materials from lignin or polysaccharides could be evidenced. Structural a...
The adsorption of a purified 20.7 kDa thermostable endo-1-4-β-xylanase (EC 3.2.1.8) from a Bacillus sp. on wheat straw at 4°C was studied. Adsorption data fitted the Langmuir-type adsorption isotherm with the maximum amount of adsorbed xylanase being 521 μg protein g−1 straw. Adsorption of the xylanase on straw, lignin, and insoluble xylans was irr...
Bacillus sp. strain XE and its mutant derivative strain D3 produce a thermostable xylanase which is suitable for enzymatic bleaching of kraft pulp. Xylanase synthesis was shown to be induced by the soluble products of xylan hydrolysis (xylooligosaccharide) and equally, catabolically-repressed when these oligosaccharides accumulate in the medium. An...
Hydrolysis of wheat stems and delignified wheat stems with a purified 20.7 kDa xylanase (EC 3.2.1.8) isolated from a Bacillus sp. yielded 18% and 70% of xylans, respectively. In order to evaluate the accessibility of the xylans and the extent of diffusion of the xylanase in wheat stems, antixylan and antixylanase polyclonal antibodies in conjunctio...
A thermophilic xylanase from Bacillus strain D3 suitable for use as a bleach booster in the paper pulping industry has been identified and characterized. The enzyme is suited to the high temperature and alkaline conditions needed for using xylanases in the pulp industry. The xylanase is stable at 60 degrees C and relatively stable at high temperatu...
A thermophilic xylanase from Bacillusstrain D3 suitable for use as a bleach booster in the paper pulping industry has been identified and characterized. The enzyme is suited to the high temperature and alkaline conditions needed for using xylanases in the pulp industry. The xylanase is stable at 60°C and relatively stable at high temperatures, with...
A xylanase of M(r) 20,700 from the hyperproductive mutant D3 of the thermophillic Bacillus, strain XE has been purified and crystallized from 2-methyl-2,4-pentanediol. The unit cell is triclinic with a = 48.5 A, b = 51.5 A, c = 72.6 A, alpha = 90.4 degrees, beta = 95.4 degrees, gamma = 92.3 degrees (all +/- 0.2). There are four molecules in the asy...
An endo-1,4-β-xylanase (E.C.3.2.1.8) fraction of high specific activity was isolated from a 180-l culture supernatant of Clostridium thermolacticum and partially purified by a one-step ion-exchange chromatography. This xylanase fraction, which contained 290 U mg−1 of protein, was used for the large-scale deploymerization of a xylan extracted from c...
An extracellular xylanase from a thermophilic anaerobe, Clostridium thermolacticum, was purified 400-fold by ion-exchange chromatography and gel filtration. The purified enzyme had a specific activity of 31,670 nkat/mg of protein at 60 degrees C, a molecular mass of 39 kDa and a pI of 4.9. The enzyme exhibited maximal activity at 80 degrees C (1 h...
In substrate-limited continuous or fed-batch cultures,Clostridium thermolacticum excreted high yield of xylanases even when readily metabolizable compounds such as glucose were used as substrate. These results demonstrated that theC. thermolacticum xylanases were constitutive and were catabolite repressed. Optimization of culture conditions showed...
Glycoproteins are present in the cell envelopes of some Eubacteria (Küpcü et al. 1984) and Archaebacteria (Mescher and Strominger 1976, Wieland et al. 1980). Among Archaebacteria, the methanogens exhibit various types of cell envelopes (Kandier and König 1985), some of them being protein surface-layers associated with carbohydrates. Methanothrix so...
An intracellular glycogen was purified and characterized from the acetoclastic bacteria Methanothrix str. FE, its average chain length was about 13 glucose residues. Acetyl-CoA was shown to be synthesized by the action of acetate thiokinase; in addition pyruvate synthase, phosphoenolpyruvate synthetase and enzymes of gluconeogenesis were detected i...
Studies on immunological relationships among Methanosarcina genus using immunofluorescence and immunoprecipitation showed that a common antigen can be extracted by shaking in aqueous phase. This antigen was purified from Methanosarcina mazei. The protein had a molecular weight of 283400 daltons with three subunits, =68000, =43200 and =30500. It con...
Hemocyanin, the copper-containing glycoprotein that serves as an oxygen carrier in the hemolymph of some arthropods and molluscs, was obtained from the blood of the scorpion Androctonus australis. Sugar analysis of the glycoprotein revealed that its carbohydrate moiety is of the N-glycosylic type. The carbohydrate chains were released from the prot...
After pronase digestion of bovine fibrinogen, the asparagine-linked glycans were released from the resulting glycopeptides by hydrazinolysis, and subsequently re-N-acetylated. Two sialylated glycans were isolated by ion-exchange chromatography. Their primary structure has been determined by methylation analysis and 360-MHz 1H-NMR spectroscopy. The...
The extent of glycans heterogeneity in a pathological human immunoglobulin M ZAJ has been studied on oligosaccharides released by hydrazinolysis from the purified glycoprotein. After reduction with NaB3H4, asparagine-linked carbohydrate chains were separated by affinity chromatography on concanavalin A-Sepharose into oligomannosidic and N-acetyllac...
The carbohydrate chains of the pathological human immunoglobulins M from two patients with Waldenström's macroglobulinemia were released by hydrazinolysis. The N-acetyllactosamine-type glycans were obtained by affinity chromatography on concanavalin A and fractionated by high-voltage paper electrophoresis. The primary structure of the major compoun...
The well-known heterogeneity of normal and pathological immunoglobulins M was investigated in a study involving the characterization of their carbohydrate moieties. Oligosaccharide units were released from the native molecule by hydrazinolysis, and they were fractionated by affinity chromatography on a concanavalin A-Sepharose column to yield separ...
N-glycosidically-linked glycans released by hydrazinolysis of human factor VIII/von Willebrand factor (FVIII/vWf) were separated by high-voltage electrophoresis. Five fractions were obtained, one of them representing 60% of the total amount of the N-glycosidically-linked glycans of FVIII/vWf. On the basis of the carbohydrate composition, methylatio...
Incubation of whole lymphocytes with UDP-N-acetyl [3H]glucosamine used as the only precursor leads to the formation of dolichyl diphosphate [3H]chitobiose, DolPP-(GlcNAc)2, and dolichyl diphosphate N-acetyl-[3H]glucosamine, DolPP-GlcNAc. Although very few dolichyl diphosphate oligosaccharides are formed, a high level of radioactivity is recovered w...
Human FVIII/vWf, purified 9 000 fold, was prepared from therapeutic concentrates by gel filtration and by immuno-affinity chromatography on insolubilized immunoglobulins isolated from a rabbit immunized with the plasma of a patient devoid of FVIII R:Ag. These preparations which contain coagulant activity and agglutinate normal washed human platelet...
The presence of sialic acid in the cell surface glycoconjugates has a crucial importance in a variety of biological cell properties. It has been involved in the electrokinetic potential of the cell [l] and in the permeability of the membrane [2]. More recently, it has been related to the social life of the cell: cell-cell recognition [3], contact i...
Experiments with rat liver microsomal galactosyltransferase has been developed to test the effect of cyclic nucleotides on the transfer activity. An overall stimulation is observed when cAMP or cGMP (concentration higher that 10(-6) M) are added to the incubation medium. However, more detailed experiments show that the cyclic nucleotides do not act...
