Showing papers on "Chitin published in 1983"
TL;DR: It is concluded that ethylene-induced chitinase functions as a defense enzyme against fungal and bacterial invaders.
Abstract: Ethylene induced an endochitinase in primary leaves of Phaseolus vulgaris L. The enzyme formed chitobiose and higher chitin oligosaccharides from insoluble, colloidal or regenerated chitin. Less than 5% of the total chitinolytic activity was detected in an exochitinase assay proposed by Abeles et al. (1970, Plant Physiol. 47, 129–134) for ethylene-induced chitinase. In ethylene-treated plants, chitinase activity started to increase after a lag of 6 h and was induced 30 fold within 24 h. Exogenously supplied ethylene at 1 nl ml−1 was sufficient for half-maximal induction, and enhancement of the endogenous ethylene formation also enhanced chitinase activity. Cycloheximide prevented the induction. Among various hydrolases tested, only chitinase and, to a lesser extent, β-1,3-glucanase were induced by ethylene. Induction of chitinase by ethylene occurred in many different plant species. Ethylene-induced chitinase was purified by affinity chromatography on a column of regenerated chitin. Its apparent molecular weight obtained by sodium dodecyl sulfate-gel electrophoresis was 30,000; the molecular weight determined from filtration through Sephadex G-75 was 22,000. The purified enzyme attacked chitin in isolated cell walls of Fusarium solani. It also acted as a lysozyme when incubated with Micrococcus lysodeikticus. It is concluded that ethylene-induced chitinase functions as a defense enzyme against fungal and bacterial invaders.
638 citations
TL;DR: Results suggest that crystallization of nascent subunits may occur by a self-assembly mechanism that was blocked by the stain.
Abstract: Summary: In the presence of calcofluor white, budding scars and dividing cross-walls of Saccharomyces cerevisiae exhibited fluorescence, indicating that the brightener was a specific marker of fungal chitin In addition, incubation of cells in the presence of the brightener did not stop protein and wall-polymer formation, but abnormal deposition of chitin occurred Chitin synthesis was normal in regenerating protoplasts of Candida albicans in the presence of calcofluor, but formation of the crystalline lattice was blocked These results suggest that crystallization of nascent subunits may occur by a self-assembly mechanism that was blocked by the stain
235 citations
TL;DR: Enzyme activity was correlated with the soil fungal population but not with numbers of actinomycetes or bacteria, and a specialized mycoflora was associated with chitin decomposition.
Abstract: Chitinase activity was determined by incubating a mixture of toluene-treated soil with 1% (w/w) colloidal chitin suspension for 18 h at 37°C and then, after dilution, assaying the amount of N-acetyl-glucosamine released. Maximal chitinase activity was observed at 45°C and optimal pH for enzymatic reaction was 5.0–5.5. Soil chitinase activity decreased with increasing soil depth and was significantly affected by crop cover and fertilization regime. Chitin added to soil stimulated chitinase activity. Enzyme activity was correlated with the soil fungal population but not with numbers of actinomycetes or bacteria. A specialized mycoflora was associated with chitin decomposition.
181 citations
TL;DR: In this article, carboxymethyl-and dihydroxypropylchitine were preprocessed in order to obtain carboxyethylmethyl- and dihydroxypyldiamethyl-CHitine.
Abstract: Preparation de carboxymethyl- et dihydroxypropylchitine. Etude des sites d'alkylation par spectrometrie RMN
142 citations
Journal Article•
TL;DR: The effect of amending soil with chitin on Meloidogyne arenaria (Neal) Chitwood was studied in a greenhouse experiment using silt loam from an infested peanut field and the soil was analyzed for soil enzymic activity and microbial populations.
Abstract: The effect of chitin on soil microflora and on nematodes was studied in microplots containing a sandy loan [pH = 6.0 and organic matter content 1% (w/w)] infested with Meloidogyne arenaria (Neal) Chitwood. Ground chitin was added to soil at rates of 0-4.0% (w/w). The chitin was allowed to decompose for 10 weeks, during which time soil samples were collected every 15 days. After 10 weeks, soil from each plot was transferred to the greenhouse and planted with 'Summer Crookneck' squash (Cucurbita pepo L.) to assess degree of root galling caused by the nematode. Chitin treatments at rates of 0.4% and above reduced root galling; however, at rates 0.8%, chitin amendments were phytotoxic to the plants. Chitin amendments at rates of 1% and above resulted in an increase in pH, conductivity, nitratenitrogen, ammoniacal-nitrogen and chitinase activity. Fungal populations were stimulated by chitin amendments at rates of 1% and above. Elements of a mycoflora previously associated with parasiti
133 citations
TL;DR: The Svennerholm modification of the Elson-Morgan method for glucosamine analysis was shown to be suitable for rapid quantitative determination of fungal chitin without chromatographic separation of hydrolysate chromogens.
Abstract: The Svennerholm modification of the Elson-Morgan method for glucosamine analysis was evaluated for its applicability to the rapid determination of chitin in wood decay fungi. The evaluation included extent of chromogen interference, sensitivity, color stability, and hydrolysis conditions for maximum release of glucosamine from fungal cell walls. With our further modification, the Svennerholm method was shown to be suitable for rapid quantitative determination of fungal chitin without chromatographic separation of hydrolysate chromogens.
125 citations
TL;DR: In this paper, a nonlinear equilibrium isotherm was used to predict theoretical concentration versus time curves of dyestuffs on chitin, and the analysis was based on a computer program.
111 citations
TL;DR: The inference that wall-binding sites were involved led to the testing of uranium uptake by chitin, cellulose, and cellulose derivatives in microcolumns, all of which were active, especially chit in particular.
Abstract: Penicillium digitatum mycelium can accumulate uranium from aqueous solutions of uranyl chloride. Azide present during the uptake tests does not inhibit the process. Killing the fungal biomass in boiling water or by treatment with alcohols, dimethyl sulfoxide, or potassium hydroxide increases the uptake capability to about 10,000 parts per million (dry weight). Formaldehyde killing does not enhance the uranium uptake. The inference that wall-binding sites were involved led to the testing of uranium uptake by chitin, cellulose, and cellulose derivatives in microcolumns. All were active, especially chitin.
107 citations
TL;DR: Chitin (β (1°4)-N-acetyl-D-glucosamine) and chitosan (deacetylated chitin) are currently available in large quantities as waste products and by-products of the shellfish industry and their potential as carriers for food additives was studied.
Abstract: Chitin (β (1°4)-N-acetyl-D-glucosamine) and chitosan (deacetylated chitin) are currently available in large quantities as waste products and by-products of the shellfish industry. Their potential as carriers for food additives was studied. Significant correlations were found between dye concentration ranging from 0.2–1.6 mg dye (FD&C Red No. 40) per g chitin or chitosan and dye-binding capacity of chitin or chitosan. Within a pH range of 2.0–7.0, dye-binding capacity of chitin was stable. Chitosan gelled below a pH of 5.5 and could not be evaluated but its dye-binding capacity was constant between pH 7.0 and 5.5. Above pH 7.0 dye-binding capacity decreased for chitin as well as for chitosan but between pH 2.0 and 6.0 no dye was released from dyed chitin containing 0.77 mg dye/g chitin.
104 citations
TL;DR: Three endochitinases have been isolated from the tobacco hornworm, Manduca sexta, by ammonium sulphate fractionation and chromatographic procedures and exhibit maximum activity around pH 6 with the oligosaccharide substrates.
89 citations
TL;DR: The results suggest that unbalanced conditions created in the cell by arresting the cycle at different stages result in generalized activation of the chitin synthetase zymogen, which may lead to consequences that are not functionally related to that event under normal conditions.
Abstract: Growth of Saccharomyces cerevisiae cell cycle mutants cdc3, cdc4, cdc7, cdc24, and cdc28 at a nonpermissive temperature (37 degrees C) resulted in increased accumulation of chitin relative to other cell wall components, as compared with that observed at a permissive temperature (25 degrees C). Wild-type cells showed the same chitin/carbohydrate ratio at both temperatures, whereas mutants cdc13 and cdc21 yielded only a small increase in the ratio at 37 degrees C. These results confirm and extend those reported by B. F. Sloat and J. R. Pringle (Science 200:1171-1173, 1978) for mutant cdc24. The distribution of chitin in the cell wall was studied by electron microscopy, by specific staining with wheat germ agglutinin-colloidal gold complexes. At the permissive temperature, chitin was restricted to the septal region in all strains, whereas at 37 degrees C a generalized distribution of chitin in the cell wall was observed in all mutants. These results do not support a unique interdependence between the product of the cdc24 gene and localization of chitin deposition; they suggest that unbalanced conditions created in the cell by arresting the cycle at different stages result in generalized activation of the chitin synthetase zymogen. Thus, blockage of an event in the cell cycle may lead to consequences that are not functionally related to that event under normal conditions.
TL;DR: Results indicate that the enzyme faces the interior of the cell, both in vivo and in vitro, and the synthase receives N-acetylglucosamine residues from UDP-N- acetamido-2-deoxy-D-glucose at the cytoplasmic face of the membrane and transfers them vectorially to a growing chain of chitin that is concomitantly extruded to the outside.
Abstract: To ascertain the directionality of chitin synthesis by yeast plasma membranes, the external surface of Saccharomyces cerevisiae protoplasts was labeled with ferritin--concanavalin A. After protoplast lysis, plasma membranes were isolated and treated with trypsin to activate chitin synthase (UDP-2-acetamido-2-deoxy-D-glucose:chitin 4-beta-acetamidodeoxy-D-glucosyl-transferase, EC 2.4.1.16). The membranes were then enrobed in agar and allowed to synthesize chitin from UDP-N-acetylglucosamine. After fixation and embedding in Epon, thin sections were stained for chitin with wheat germ agglutinin--colloidal gold complexes. The chitin marker was found near the ferritin-labeled external face of the membrane--i.e., the polysaccharide was located on the outside of the membrane, as it is in the intact cell. Chitin synthase activity was not detected in intact protoplasts before or after treatment with trypsin. The enzyme became available to trypsin activation after lysis of the protoplasts. Together with similar, previously reported experiments on the inactivation of chitin synthase by glutaraldehyde, these results indicate that the enzyme faces the interior of the cell. We conclude that, both in vivo and in vitro, the synthase receives N-acetylglucosamine residues from UDP-N-acetylglucosamine at the cytoplasmic face of the membrane and transfers them vectorially to a growing chain of chitin that is concomitantly extruded to the outside.
TL;DR: Chitin synthetase, initially very low, was incorporated in important amounts into cell membranes mainly in a zymogenic state and was the most abundant polymer found in the aberrant wall of the regenerating protoplast of Candida albicans.
Abstract: The transition of blastospores to the mycelial phase in Candida albicans was induced after the blastospores were kept at 4 degrees C for several hours and then transferred to a fresh medium prewarmed at 37 degrees C. Glucan was the most abundant polymer in the wall in the two morphogenetic forms but the amount of chitin was higher in the mycelial form than in blastospores. Efficient protoplasting required reducing agents and proteases together with beta-glucanases (zymolyase). Protein synthesis in regenerating protoplasts was initiated after about 30 min. Chitin synthetase, initially very low, was incorporated in important amounts into cell membranes mainly in a zymogenic state. After a few hours chitin was the most abundant polymer found in the aberrant wall of the regenerating protoplast.
TL;DR: In this article, the amount of dye adsorbed per gram of chitin has been plotted against the square root of time, and the slope of this plot is linear and has been defined as a rate parameter k.
Abstract: Intraparticle diffusion processes for the adsorption of dyestuffs onto chitin have been studied. The amount of dye adsorbed per gram of chitin has been plotted against the square root of time. The slope of this plot is linear and has been defined as a rate parameter k. This rate parameter has been determined for a number of process variables, including initial dye concentration, agitation, chitin particle size, chitin mass, temperature, and solution pH. However, sometimes two and even three linear regions are apparent on the root time plots indicating a possible branched pore mechanism. The controlling mechanisms are due to macropores and micropores in the chitin particle creating rapidly and slowly diffusing regions.
TL;DR: Several methods for the rapid determination of the degree of acetylation of chitin and related polymers have been evaluated, including the use of the infrared and the mass spectra as discussed by the authors.
Abstract: Several methods for the rapid determination of the degree of acetylation of chitin and related polymers have been evaluated, including the use of the infrared and the mass spectra.
Patent•
26 Jul 1983
TL;DR: A chitin-protein complex is prepared from chit-containing biological waste material such as crustacean shells, which has useful nematostatic and nematocidal activity for agricultural and horticultural applications as discussed by the authors.
Abstract: A chitin-protein complex is prepared from chitin-containing biological waste material such as crustacean shells. The complex is different from both chitin and chitosan, and has useful nematostatic and nematocidal activity for agricultural and horticultural applications by admixing nematocidally effective amounts with a plant growth medium. The complex also provides a source of nitrogen in slow-release form, making it particularly suitable for combination with fertilizers, soil conditioners, etc.
TL;DR: It was confirmed that the ground mixture of phenytoin-chitosan gave enhanced bioavailability of phenYtoin in beagle dogs.
Abstract: With a view to application of chitin and chitosan to pharmaceutical preparations, the dissolution and bioavailability of ground mixtures of phenytoin with chitin or chitosan were investigated. Ground mixtures of phenytoin with chitin, chitosan and crystalline cellulose in 1 : 2 weight ratio were prepared by co-grinding in a ball mill. The X-ray diffraction patterns suggested that the size of crystals of phenytoin was decreased in the ground mixtures. The dissolution rate of phenytoin from the ground mixtures was significantly greater than that from physical mixtures or intact phenytoin powder. The ground mixture with chitosan showed fastest dissolution, followed by that with chitin and then that with crystalline cellulose. The dissolution of phenytoin from tablets of the ground mixture with chitin or chitosan was greater than that from tablets of the physical mixture, while that from tablets of the ground mixture with crystalline cellulose was significantly smaller than that from tablets of the physical mixture. It was confirmed that the ground mixture of phenytoin-chitosan gave enhanced bioavailability of phenytoin in beagle dogs.
TL;DR: Sterilization of chitin by autoclaving or boiling causes release of d -glucosamine and N -acetylglucOSamine from the macromolecule and these solubilized components actually function as the inducers for synthesis of Chitinase.
TL;DR: Chitin microfibrils exposed by chemical extraction of hyphal walls of Candida albicans, Histoplasma capsulatum, Blastomyces dermatitidis, Paracoccidiodes brasiliensis, Coprinus cinereus andMucor mucedo were of variable morphology but gave identical infrared spectra and behaved as pure chitin in chromatographic analyses.
Abstract: Chitin microfibrils exposed by chemical extraction of hyphal walls ofCandida albicans, Histoplasma capsulatum, Blastomyces dermatitidis, Paracoccidiodes brasiliensis, Coprinus cinereus andMucor mucedo were of variable morphology but gave identical infrared spectra and behaved as pure chitin in chromatographic analyses The microfibrils of the four dimorphic fungi studied were shorter than those in the mouldsC cinereus andM mucedo but were similar to those reported for the yeastSaccharomyces cerevisiae InC albicans the microfibrils in the septal plates of hyphae were predominantly tangentially orientated and were longer than those in the lateral walls Microfibrils produced by chitin synthasein vitro were very much longer than any observed from hyphal preparations
TL;DR: The results suggest 3H-N-acetylglucosamine-labeled oligosaccharide-lipids are distinct from the mannose-labeling fraction and may participate in the formation of an endogenous primer for chitin synthesis after their transfer to a protein acceptor.
TL;DR: The resulting carboxymethyl-chitin (CM- chitin) was found to bind calcium ions specifically among alkali-earth metals even in the presence of monovalent cations such as sodium or potassium.
Abstract: Carboxymethylation of chitin was carried out effectively for preparing a cation exchange resin under basic conditions. The resulting carboxymethyl-chitin (CM-chitin) was found to bind calcium ions specifically among alkali-earth metals even in the presence of monovalent cations such as sodium or potassium. Differential IR absorption spectroscopy suggested that the binding of calcium ion by carboxyl groups was assisted by acetamide groups at C2 and primary hydroxyl groups at C6 or secondary hydroxyl groups at C3 in the N-acetylglucosamine residue. The binding constants were estimated at various ionic strengths and ion concentrations. The selectivity coefficient (KNaCa) of CM-chitin for calcium ions over sodium ions was assumed to be 45.6 at neutral pH and 0.1—0.2 of ionic strength. The fibrous CM-chitin was prepared to investigate the effects of an increase in the number of surface ionic sites and degree of orientation on the binding capacity. The results indicated a marked enhancement.
TL;DR: Six analogues of polyoxin L were synthesized from uridine, and analogues containing aromatic amino acid residues were the most efficient inhibitors of chitin synthetase.
Abstract: Six analogues of polyoxin L were synthesized from uridine. All of these analogues inhibited chitin synthetase from Candida albicans. Derivatization of the amine terminus of the polyoxin analogues resulted in loss of activity, and analogues containing aromatic amino acid residues were the most efficient inhibitors of chitin synthetase. The concentration of tryptophanyl uracil polyoxin C, 8, which caused 50% inhibition of chitin synthetase activity, was 1.6 X 10(-6) M. This was virtually identical with the activity found for polyoxin D. None of the inhibitors effectively competed with the entry of (Met)3 into C. albicans. All of the analogues caused severe morphological distortions of the yeast in culture, and a number of analogues killed C. albicans at millimolar concentrations. The results suggest that chitin synthetase inhibitors may have potential as anticandidal drugs.
TL;DR: It is suggested that the light growth response in the sporangiophore from Phycomyces is due to a transient softening of thecell wall at the growing region followed by an elongation due to the turgor pressure of the cell and an enhanced chitin biosynthesis by the apically localized chit in synthetase which restores normal strength to the cell wall.
TL;DR: Evidence for a lipid dependence of membrane-associated chitin synthase in Schizophyllum commune is based on the following observations: Arrhenius plots of the temperature dependence of this enzyme showed deflections from linearity that are characteristic for lipid-affected membrane-bound enzymes.
Abstract: Evidence for a lipid dependence of membrane-associated chitin synthase inSchizophyllum commune is based on the following observations: Arrhenius plots of the temperature dependence of this enzyme showed deflections from linearity that are characteristic for lipid-affected membrane-bound enzymes. The activity of chitin synthase dissociated by digitonin decreased at increasing digitonin/protein ratios and could be restored by addition of egg lecithin. After further delipification by sucrose gradient centrifugation, enzyme activity progressively decreased, banded at higher densities, and was less effectively restored by lecithin. The activity of dissociated chitin synthase was also restored by soybean phosphatidylcholine and low concentrations of phosphatidylinositol and phosphatidylserine. At higher concentrations, phosphatidylinositol and phosphatidylserine were inhibitory. Lysophosphatidylcholine and phosphatidylethanolamine were slightly stimulatory, whereas no effect resulting from ergosterol was observed.
TL;DR: A fraction which inhibited chitin synthesis was partially purified from Neurospora crassa by ammonium sulphate precipitation and gel filtration and exhibited endo- and exo-chitinase properties and was localized mainly in the cytosol fraction.
Abstract: Summary: A fraction which inhibited chitin synthesis was partially purified from Neurospora crassa by ammonium sulphate precipitation and gel filtration. This preparation possessed chitinase activity and hydrolysed either nascent or preformed chitin. Utilization of UDP-N-acetylglucos-arnine by chitin synthase was not modified in the presence of the chitinase preparation, although the chitin being synthesized was degraded mainly to N-N'-diacetylchitobiose, other larger oligosaccharides and small amounts of N-acetylglucosamine. The enzyme exhibited endo- and exo-chitinase properties and was localized mainly in the cytosol fraction. Its pH optimum was 6.7 and its apparent molecular weight 20600 Dal.
TL;DR: Removal of digitonin from preparations of isolated 16 S chitosomal subunits results in the formation of chitin-synthesizing particles that are ultrastructurally and biochemically indistinguishable from native chitOSomes, with the exception of their having an average s value of 130.
TL;DR: In this paper, the dissolution behavior of ground mixtures of prednisolone with chitin and chitosan was investigated, and the results indicated that chitins and Chitosans can improve the dissolution properties of the ground mixture.
Abstract: With a view to an application of chitin and chitosan to pharmaceutical preparations, the dissolution behavior of ground mixtures of prednisolone with chitin and chitosan was investigated. Ground mixtures of prednisolone with chitin and chitosan were prepared by cogrinding in a ball mill. The X-ray diffraction patterns and results of differential scanning calorimetry suggested that the size of crystals of prednisolone was decreased in the ground mixtures. The dissolution rate of prednisolone from the ground mixtures was significantly greater than that from the physical mixture or from intact prednisolone powder. These results indicate that chitin and chitosan can improve the dissolution properties of prednisolone.
TL;DR: In the study of natural chitin metabolism by a strain of Streptomyces, the different extracellular chitinolytic enzymes synthetised by the microorganism are separated by affinity chromatography.
TL;DR: This is the first report of a cell-free chitin-synthesizing system derived from insect tissue which is sensitive to inhibition by diflubenzuron, and some radioactivity also becomes incorporated into non-chitin products in this system.
Abstract: Chitin synthase activity has been demonstrated in crude homogenates of larval integuments from L. cuprina and in similar preparations from Musca domestica and Calliphora erythrocephala. This is the first report of an insect integumental chitin synthase. This activity brings about the incorporation of radioactivity from UDP-N-acetyl-[14C]glucosamine into an ethanol- and alkali-insoluble form. A major part of this labelled product has been characterized as chitin by its insolubility in alkali, resistance to degradation by proteases and its susceptibility to digestion by chitinase and RCI. Most of the radioactivity solubilized during digestion by chitinase co-migrates with N-acetylglucosamine, glucosamine and chitobiose during paper chromatography. Some radioactivity also becomes incorporated into non-chitin products in this system. There is substantial evidence that incorporation is not brought about by whole epidermal cells or by microbial contamination in the homogenates. The extent of incorporation obtained with the homogenates is limited by the presence of degradative enzymes which rapidly break down the substrate (UDP-N-acetylglucosamine). The incorporation was partially inhibited (50-70%) by both polyoxin-D (apparent Ki 0'04I1M) and diftubenzuron (apparent Ki 5-8 11M). This is the first report of a cell-free chitin-synthesizing system derived from insect tissue which is sensitive to inhibition by diftubenzuron.
TL;DR: It is suggested that chitin is important in maintaining the structural integrity of the spherule phase, but the role of chit in the mycelial phase is less clear.
Abstract: The cell walls of both growth phases of Coccidioides immitis were studied by light and electron microscopy and biochemical procedures in an effort to assess the role of chitin in the fungus. Inhibition of normal chitin synthesis in the spherule by exposure to several concentrations of polyoxin D (PD) led to multiple morphological effects. Exposure of the mycelial phase to significantly higher levels of the compound had no morphological effect, as determined by autoradiography and light and electron microscopy. However, when equal masses of both morphological phases were treated with PD and pulsed with labeled N-acetylglucosamine, there was a greater relative (percent) reduction of incorporation of label in PD-treated mycelia compared with that of spherules. Nevertheless, the treated and untreated mycelia incorporated severalfold more counts than did corresponding spherules. The results suggest that chitin is important in maintaining the structural integrity of the spherule phase, but the role of chitin in the mycelial phase is less clear.