Showing papers on "Chitinase 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: 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
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: 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.
55 citations
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.
43 citations
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.
31 citations
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.
28 citations
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.
28 citations
TL;DR: Cells from the continuous MRRL-CH line derived from embryos of the tobacco hornworm synthesized chitin and the presence of chitobiose was confirmed by gas chro-matography-mass spectrometry.
Abstract: Cells from the continuous MRRL-CH line derived from embryos of the tobacco hornworm synthesized chitin. Digestion of the washed pellet from [14C]-N-acetylglucosamine-labeled cells by chitinase yielded a water-soluble labeled compound. The lyophilized residue from the supernatant of the chitin digestion was analyzed by gas-liquid chromatography as its trimethylsilyl derivative. The major component cochromatographed with derivitized chitobiose. The presence of chitobiose was confirmed by gas chro-matography-mass spectrometry. The synthesis of chitin by this cell line is inhibited by diflubenzuron.
26 citations
TL;DR: Virulence and resistance may act on the same biochemical mechanisms and, because Erwinia-virulence on potato depends on the lysis of cell walls of the host, resistance may depend on theLysis of cells of the parasite.
Abstract: Virulence and resistance may act on the same biochemical mechanisms. Because Erwinia-virulence on potato depends on the lysis of cell walls of the host, resistance may depend on the lysis of cell walls of the parasite. An example is given with yellow rust on wheat.
21 citations
TL;DR: Two morphologically distinct forms of chitin were found in the arthrospore walls and septa of Trichophyton mentagrophytes as discussed by the authors, including microfibrillar and non-fibriliar.
Abstract: Two morphologically distinct forms of chitin were found in the arthrospore walls and septa of Trichophyton mentagrophytes. Two-thirds of the total wall chitin was the microfibrillar and chitinase-sensitive form. The remaining chitin existed in a previously uncharacterized "nonfibrillar" form and was insensitive to the action of Streptomyces chitinase. Exhaustive digestion of the arthrospore walls and septa with beta (1 leads to 3)-glucanase and chitinase followed by extraction with NaOH (1 N, 100 degrees C, 3 h) resulted in a fraction which retained the original wall shape. This fraction consisted of 85% N-acetylglucosamine, 2.0% galactosamine, 2.5% glucose, and 0.4% amino acids, 74% of which were lysine. Both its infrared spectrum and its X-ray diffraction pattern were almost identical to those of authentic chitin. There was no evidence of the presence of muramic acid, hexuronic acid, phosphate, or sulfate in this fraction. Its resistance to chitinase was due neither to the presence of protective wall layers or melanin nor to its close or covalent association with beta-glucan. Aside from its nonfibrillarity, this hexosamine polymer differed from authentic chitin in that it was soluble in 6 N HCl and 7.5 N NaOH. The development of this nonfibrillar chitin layer in the cell wall during arthrosporogenesis of T. mentagrophytes may be related to the arthrospores being resistant to a variety of antifungal agents.
TL;DR: Cell wall-associated, chitin-binding hemagglutinin (endo-CLA) was liberated from the cell wall with β-glucanase but not with chit inase, cellulase, protease, sodium chloride, 2-mercaptoethanol, hydrochloric acid, N-acetyl-D-glUCosamine or chitooligosaccharides.
Abstract: The cell wall of Conidiobolus lamprauges is composed of D-glucosamine, D-glucose and d-mannose in the ratio of 1:1:1. The first sugar originated from chitin and a part of the second sugar came from β-glucan.Cell wall-associated, chitin-binding hemagglutinin (endo-CLA) was liberated from the cell wall with β-glucanase but not with chitinase, cellulase, protease, sodium chloride, 2-mercaptoethanol, hydrochloric acid, N-acetyl-D-glucosamine or chitooligosaccharides.Endo-CLA and extracellular CLA (exo-CLA) showed almost the same sugar specificity and immunological properties in the hemagglutination inhibition test and the double immunodiffusion test, respectively.Endo-CLA was detected in the cell wall before production of β-glucanase by this organism, whereas exo-CLA was produced in the culture filtrate simultaneously with the enzyme.These results suggest that CLA was liberated from the β-glucan matrix in the cell wall by the action of β-glucanase.
TL;DR: Two possibilities are suggested i) cell walls, especially inner wall layers, of control and polyoxin-treated hyphae may have different structural constituents, and ii) melanin-like pigments in inner cell walls may be associated with the resistance of poly toxin-treatedhyphae to lysis by digestive enzymes.
Abstract: Polyoxin-B-treated and untreated (control) hypae of Alternaria kikuchiana Tanaka were first degraded with 2N NaOH, 1N H2SO4, and digestive enzymes, and then morphological alterations of the cell walls were investigated by cytochemical methods and electron microscopy. A pronounced difference between control and treated hyphae was seen after sequential treatment with NaOH-H2SO4-NaOH. Inner wall layers of controls were transformed into numerous microfibrils; these were identified, in turn, by chitinase and Lytic enzyme digestions as chitin and β-1, 3-glucan intermixed with protein. But these same treatments failed to structurally degrade the walls of polyoxin-treated hyphae. In the controls, only the thin outer wall layer showed any resistance to the treatment, but in polyoxin-treated hyphae the entire cell wall, including septae and walls of intracellular hypha, was resistant to a sequence of the degradative treatments. Cytochemical tests revealed that both control and polyoxin-treated hyphae, which originally contained chitin, no longer responded positively to tests for chitin after chitinase or HCl treatment following treatment with the NaOH-H2SO4-NaOH sequence. This study suggests two possibilities i) cell walls, especially inner wall layers, of control and polyoxin-treated hyphae may have different structural constituents, and ii) melanin-like pigments in inner cell walls may be associated with the resistance of polyoxin-treated hyphae to lysis by digestive enzymes.
TL;DR: PRs from different plant genera displayed a similar but not identical range of relative mobilities in both native and SDS gels, whereas bean chitinase and apple agglutinin were clearly different.
Abstract: Preparations of pathogenesis-related (b) proteins (PRs) from differentNicotiana species, tomato,Gynura aurantiaca, bean, and cowpea were compared to each other and to bean chitinase and a constitutive apple agglutinin by electrophoresis in polyacrylamide gels both in the absence and in the presence of SDS, and by serological double diffusion analysis using antisera against tobacco PRs and bean chitinase. PRs from different plant genera displayed a similar but not identical range of relative mobilities in both native and SDS gels, whereas bean chitinase and apple agglutinin were clearly different. None of the antisera reacted with any of the PR preparations from plant genera other than the one from which the antigen(s) had been derived. Whilst PRs within the genusNicotiana are serologically related and can be identical, PRs from different plant genera seem to be sufficiently different to be considered as genus-specific.