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Showing papers on "Chitin published in 1990"


Journal ArticleDOI
01 Jan 1990
TL;DR: It appears, this novel biomolecule, biodegradable, and biocompatible, find applications in substituting or regenerating the blood/tissue interfaces.
Abstract: Chitosan [a (1----4) 2-amino-2-deoxy-beta-D-Glucan] is a unique polysaccharide derived from chitin. Several attempts have been made to use this biopolymer in biomedical field. The use of this material in the development of hemodialysis membranes, artificial skin, drug targetting and other applications are discussed. It appears, this novel biomolecule, biodegradable, and biocompatible, find applications in substituting or regenerating the blood/tissue interfaces. This polysaccharide having structural characteristics similar to glycosaminoglycans, seems to mimic their functional behaviour.

728 citations


Journal ArticleDOI
TL;DR: Examination by electron microscopy showed that microbial cells exposed to N-carboxybutyl chitosan underwent marked morphological alterations, which are of importance in defining the suitability of N- carboxy butyl ch itosan as a wound dressing.
Abstract: N-Carboxybutyl chitosan, a modified chitin of crustacean origin, displayed inhibitory, bactericidal, and candidacidal activities when tested against 298 cultures of various pathogens. Examination by electron microscopy showed that microbial cells exposed to N-carboxybutyl chitosan underwent marked morphological alterations. The data are of importance in defining the suitability of N-carboxybutyl chitosan as a wound dressing.

421 citations


Journal ArticleDOI
TL;DR: A reliable colorimetric microassay adapted to microtitre plates was established, based on the precipitability of carboxymethyl-chitin-Remazol Brilliant Violet 5R from buffered solutions with hydrochloric acid.

292 citations


Journal ArticleDOI
TL;DR: Chitin is produced in enormous quantities in the biosphere, chiefly as the major structural component of most fungi and invertebrates, and its degradation is chiefly by bacteria and fungi, by chitinolysis via chitinases, but also via deacetylation to chitosan, which is hydrolysed by chitonases.
Abstract: Chitin is produced in enormous quantities in the biosphere, chiefly as the major structural component of most fungi and invertebrates. Its degradation is chiefly by bacteria and fungi, by chitinolysis via chitinases, but also via deacetylation to chitosan, which is hydrolysed by chitosanases. Chitinases and chitosanases have a range of roles in the organisms producing them: autolytic, morphogenetic or nutritional. There are increasing examples of their roles in pathogenesis and symbiosis. A range of chitinase genes have been cloned, and the potential use for genetically manipulated organisms over-producing chitinases is being investigated. Chitinases also have a range of uses in processing chitinous material and producing defined oligosaccharides.

275 citations


Journal ArticleDOI
TL;DR: The structure and properties of chitin and chitosan are discussed in detail in this article, where commercial sources, production, and uses, structure, and properties are discussed.
Abstract: Occurrence and biosynthesis, commercial sources, production, and uses, structure and properties of chitin and chitosan.

229 citations


Journal ArticleDOI
TL;DR: It was concluded that chitinase A1 is the key enzyme in the chit inase system of this bacterium.
Abstract: Bacillus circulans WL-12, isolated as a yeast cell wall-lytic bacterium, secretes a variety of polysaccharide-degrading enzymes into culture medium. When chitinases of the bacterium were induced with chitin, six distinct chitinase molecules were detected in the culture supernatant. These chitinases (A1, A2, B1, B2, C, and D) showed the following distinct sizes and isoelectric points: Mr 74,000, pI 4.7 (A1); Mr 69,000, pI 4.5 (A2); Mr 38,000, pI 6.6 (B1); Mr 38,000, pI 5.9 (B2); Mr 39,000, pI 8.5 (C); and Mr 52,000, pI 5.2 (D). Among these chitinases, A1 and A2 had the highest colloidal-chitin-hydrolyzing activities. Chitinase A1 showed a strong affinity to insoluble substrate chitin. Purified chitinase A1 released predominantly chitobiose [(GlcNAc)2] and a trace amount of N-acetylglucosamine (GlcNAc) from colloidal chitin. N-terminal amino acid sequence analysis of chitinases A1 and A2 indicated that chitinase A2 was generated from chitinase A1, presumably by proteolytic removal of a C-terminal portion of chitinase A1. Since chitinase A2 did not have the ability to bind to chitin, the importance of the C-terminal region of chitinase A1 to the strong affinity of chitinase A1 to substrate chitin was suggested. Strong affinity of the chitinase seemed to be required for complete degradation of insoluble substrate chitin. From these results, it was concluded that chitinase A1 is the key enzyme in the chitinase system of this bacterium.

229 citations


Journal ArticleDOI
TL;DR: End products of chitosan hydrolysis by each of the three chitOSanases were identified as glucosamine oligomers, similar to those obtained for previously reported chITosanase digestions.
Abstract: Bacillus megaterium P1, a bacterial strain capable of hydrolyzing chitosan, was isolated from soil samples. Chitosan-degrading activity was induced by chitosan but not by its constituent d-glucosamine. Extracellular secretion of chitosanase reached levels corresponding to 1 U/ml under optimal conditions. Three chitosan-degrading proteins (chitosanases A, B, and C) were purified to homogeneity. Chitosanase A (43 kilodaltons) was highly specific for chitosan and represented the major chitosan-hydrolyzing species. Chitosanases B (39.5 kilodaltons) and C (22 kilodaltons) corresponded to minor activities and possessed comparable specific activities toward chitosan, chitin, and cellulose. Chitosanase A was active from pH 4.5 to 6.5 and was stable on the basis of activity up to 45°C. The optimum temperature for enzymatic chitosan hydrolysis was 50°C. Kinetic studies on chitosanase A suggest that the enzyme is substrate inhibited. The apparent Km and Vmax determined at 22°C and pH 5.6 were 0.8 mg/ml and 280 U/mg, respectively. End products of chitosan hydrolysis by each of the three chitosanases were identified as glucosamine oligomers, similar to those obtained for previously reported chitosanase digestions.

131 citations


Journal Article
TL;DR: Surprisingly, SCM-chitin III could inhibit type IV collagenolytic activity of tumor cells more potently than heparin, and may provide a promising basis for the prevention of cancer metastasis.
Abstract: We have investigated the effects of sulfated chitin derivatives and heparin on the invasion of B16-BL6 melanoma cells through reconstituted basement membrane Matrigel which contains laminin, type IV collagen, heparan sulfate proteoglycan, and entactin. 6-O-sulfated chitin (S-chitin) and 6-O-sulfated and carboxymethyl chitin (SCM-chitin) significantly inhibited the penetration of tumor cells through Matrigel in parallel with the increased degree of sulfation. However, 6-O- and N-sulfated but partially N-deacetylated chitin derivative (SCM-chitosan) and CM-chitin had no effect. SCM-chitin with a high degree of sulfation (SCM-chitin III), which exhibited fairly low levels of anticoagulant activity, was more effective than intact heparin. SCM-chitin III and heparin were also shown to block the attachment and migration of tumor cells to laminin-coated substrates, which are considered to be involved in tumor invasion. The inhibition of cell attachment and migration by SCM-chitin III and heparin is likely to depend upon their specific binding to laminin molecules (possibly the heparin-binding domain). Degradation of heparan sulfate by heparanase was inhibited by SCM-chitin III and heparin in a dose-dependent manner. Surprisingly, SCM-chitin III could inhibit type IV collagenolytic activity of tumor cells more potently than heparin. Thus, nontoxic SCM-chitin III of low anticoagulant properties may provide a promising basis for the prevention of cancer metastasis.

120 citations


Journal ArticleDOI
TL;DR: The double disruption mutant of Saccharomyces cerevisiae has no detectable chitin deficiency in vivo, as judged by quantitative assay and by staining cells with Calcofluor, and assay of membrane preparations from thedouble disruption mutant indicates the presence of chit in synthetic activity.
Abstract: In Saccharomyces cerevisiae, the polysaccharide chitin forms the primary division septum between mother cell and bud. Two related enzymes, chitin synthase I and chitin synthase II (UDP-acetamido-2-deoxy-D-glucose:chitin 4-beta-acetamidodeoxyglucosyltransferase, EC 2.4.1.16), have been identified and their structural genes, CHS1 and CHS2, respectively, have been cloned and sequenced. Gene disruption experiments led to the conclusion that CHS2 is essential for cell division [Silverman, S.J., Sburlati, A., Slater, M.L. & Cabib, E. (1988) Proc. Natl. Acad. Sci. USA 85, 4735-4739], whereas CHS1 is not. We repeated the disruption of CHS2 and determined that it is not essential for vegetative growth. The viability of chs1::HIS3 chs2::TRP1 spores is influenced by strain background and germination conditions. The double disruption mutant has no detectable chitin deficiency in vivo, as judged by quantitative assay and by staining cells with Calcofluor. Assay of membrane preparations from the double disruption mutant indicates the presence of chitin synthetic activity. Unlike the CHS gene products, this third activity is not stimulated by trypsin. Characterization of the double disruption mutant revealed abnormalities in morphology and nuclear migration.

110 citations


Journal ArticleDOI
TL;DR: The results imply that some mycorrhizal fungi may be involved in recycling of N from this structural component of hyphal walls in soil as well as the possible role of chitinase activity in influencing fungal interactions in heathland ecosystems.

110 citations


Journal ArticleDOI
TL;DR: P pH‐activity profiles showed that yeast and hyphae contain a protease‐dependent activity that has an optimum at pH 6.8 and there is an activity that is not activated by proteolysis in vitro and which shows a peak at pH 8.0, suggesting there are two distinct chitin syntheses in C albicans.
Abstract: Chitin synthase activity was studied in yeast and hyphal forms of Candida albicans. pH-activity profiles showed that yeast and hyphae contain a protease-dependent activity that has an optimum at pH 6.8. In addition, there is an activity that is not activated by proteolysis in vitro and which shows a peak at pH 8.0. This suggests there are two distinct chitin synthases in C. albicans. A gene for chitin synthase from C. albicans (CHS1) was cloned by heterologous expression in a Saccharomyces cerevisiae chs1 mutant. Proof that the cloned chitin synthase is a C. albicans membrane-bound zymogen capable of chitin biosynthesis in vitro was based on several criteria. (i) the CHS1 gene complemented the S. cerevisiae chs1 mutation and encoded enzymatic activity which was stimulated by partial proteolysis; (ii) the enzyme catalyses incorporation of [14C]-GlcNAc from the substrate, UDP[U-14C]-GlcNAc, into alkali-insoluble chitin; (iii) Southern analysis showed hybridization of a C. albicans CHS1 probe only with C. albicans DNA and not with S. cerevisiae DNA; (iv) pH profiles of the cloned enzyme showed an optimum at pH 6.8. This overlaps with the pH-activity profiles for chitin synthase measured in yeast and hyphal forms of C. albicans. Thus, CHS1 encodes only part of the chitin synthase activity in C. albicans. A gene for a second chitin synthase in C. albicans with a pH optimum at 8.0 is proposed. DNA sequencing revealed an open reading frame of 2328 nucleotides which predicts a polypeptide of Mr 88,281 with 776 amino acids. The alignment of derived amino acid sequences revealed that the CHS1 gene from C. albicans (canCHS1) is homologous (37% amino acid identity) to the CHS1 gene from S. cerevisiae (sacCHS1).

Journal ArticleDOI
TL;DR: It is concluded that the probe accessibility to the substrate changes on the in toto hyphae and on the thin sections and that the thick-walled hyphAE have their chitin partially hidden by non-chitinous cell wall components.

Journal ArticleDOI
TL;DR: The results of this study showed that the CDDP content increased with increasing chitosan concentration and that the incorporation of chitin in the carrier matrix produced a more pronounced increase in drug content.
Abstract: To increase cisplatin (CDDP) content, to suppress burst effect during the initial phase of drug release, and to improve the capacity of the system for sustained release, we prepared various types of CDDP chitosan microspheres incorporating chitin and investigated the content of CDDP and its in vitro release kinetics from these microspheres. The results of this study showed that the CDDP content increased with increasing chitosan concentration and that the incorporation of chitin in the carrier matrix produced a more pronounced increase in drug content. The addition of chitin also led to inhibition of the initial burst effect. The rate of CDDP release reduced with increasing concentration of chitosan: that is, the 50% CDDP release time was about 0.5 h with the microspheres prepared with 1.0% of chitosan and about 4.5 h with those prepared with 5.0% of chitosan, indicating about nine-fold prolongation. The addition of chitin further resulted in retardation of the rate of CDDP release. Meanwhile, our chitosan microspheres were shown to undergo enzymatic degradation by lysozymes.

Journal ArticleDOI
TL;DR: Application of thermo‐mechano‐chemical technology to chitin deacetylation to produce chitosan did not appear to produce significant secondary products, and based on enzymatic digestibilities, the alkaline aqueous high shear process does not appears to producesignificant secondary products.
Abstract: Chitosan, the deacetylated derivative of chitin, was until recently produced by hydrolysis in 50% (w/v) NaOH. Application of thermo-mechano-chemical technology to chitin deacetylation was evaluated as an alternative method of chitosan production. This process consists of a cascade reactor unit operating under reduced alkaline conditions of 10% (w/v) NaOH. Prior mercerization of chitin at 4 degrees C for 24 h was required for high deacetylation yields. Sudden decompression of the aqueous alkaline suspension of mercerized chitin resulted in near complete deacetylation of chitin. Reactor residence time was 90 s at 230 degrees C prior to decompression. The chitosan produced was characterized by elemental analysis, (13)C-NMR and enzymatic depolymerization. Enzymatic determination of the degree of acetylation of chitin/chitosan mixtures was also investigated. Relative chitinase and/or chitosanase digestibilities were shown to be strongly dependent on chitin deacetylation. Based on enzymatic digestibilities, the alkaline aqueous high shear process does not appear to produce significant secondary products. Correlation of chitosanase digestibility with percentage of deacetylation provides a simple biological assay to study chitosan composition.

Journal ArticleDOI
TL;DR: Hydrolysis of chitosan by nitrous acid followed by Calcofluor staining yielded dark (nonfluorescent) bands (chitin deacetylase activities) in the fluorescent chitin-containing gel, which revealed the presence of several chit in de acetylases from Zygomycetes.

Journal ArticleDOI
TL;DR: In this article, the basic characteristics of chitin are described, including its synthesis and degradation, and the hormonal regulation of Chitin metabolism, and some recently detected compounds are described.
Abstract: Chitin is an important component of the exoskeleton of arthropods and of the egg shell in nematodes, but it does not occur in vertebrates. Therefore, it represents a useful target for drugs against ectoparasitic crustaceans, insects and endoparasitic nematodes. In this review we describe the basic characteristics of chitin, chitin synthesis and degradation and the hormonal regulation of chitin metabolism. Substances interfering with chitin metabolism like benzoylphenyl-urea derivatives but also some recently detected compounds are described. The necessity for a more detailed understanding of chitin metabolism and the establishment of better model systems, like e.g. chitin producing insect cell lines, is stressed and some examples are given in this review.

Journal ArticleDOI
TL;DR: DCTEM appears to be a general and straightforward technique to visualize chitin crystals in a variety of specimens to study cross sections of the ovipositor of the fly and the crab cuticle.

Journal ArticleDOI
TL;DR: Analysis of the initial products from the digestion of [ 3 H]chitin indicated that all the isozymes were endo in action, with oligomers from the dimer up to at least the decamer being evident in the digests; minor differences were observed between the iszymes in the relative proportions of the oligomeric products.

Journal ArticleDOI
TL;DR: Immobilized matrix complexes, prepared by crosslinking soluble matrix to decalcified crab carapace, promoted CaCO3 formation in that crystallization in the presence of the immobilized soluble matrix complexes began sooner than in solution controls.
Abstract: Soluble organic matrix isolated from dorsal carapaces of the blue crab, Callinectes sapidus, inhibited CaCO3 crystallization when free in solution. Immobilized matrix complexes, prepared by crosslinking soluble matrix to decalcified crab carapace, promoted CaCO3 formation in that crystallization in the presence of the immobilized soluble matrix complexes began sooner than in solution controls. In the experimental treatments, deposition of crystals occured only within the complexes and not in the crystallization solutions. Chitin, a polymer of N-acetyl-D-glucosaminc, and chitosan, a deacetylated chitin, which are both insoluble products of the organic matrix of the crab carapace containing little to no matrix protein, did not promote CaCO3 crystallization. Complexes of immobilized polyanionic synthetic peptides on chitosan also promoted CaCO3 crystallization. Addition of a hydrophobic tail (Ala8) to the polyanionic peptide (Asp20) reduced the rate of promotion, possibly because the hydrophobic tail formed a diffusion barrier around crystal nuclei growth sites, suppressing interactions of nascent crystal nuclei with ions in the bulk solution.

Book ChapterDOI
01 Jan 1990
TL;DR: The antifungal actions to be discussed here, of the very specific polyoxins and nikkomycins and of purified chit inases, are ample proof of the essential nature of chitin in fungal growth.
Abstract: Chitin, the (l→4)-β-linked homopolymer of N-acetyl-D-glucosamine, is a characteristic component of the cell walls of nearly all zoopathogenic and phytopathogenic fungi, and also of the skeletal structures of most invertebrates. As vertebrates and higher plants do not produce this polysaccharide, chitin metabolism is an attractive target for antifungal agents and pesticides (Gooday 1977). A clear analogy is with the peptidoglycan of bacterial walls, the synthesis of which is inhibited by many antibacterial agents, notably the β-lactams, and the structure of which is attacked by the defensive enzyme, lysozyme. In the case of chitin we find that nature has exploited the potential of chitin as a target, with the antifungal antibiotics, polyoxins and nikkomycins, produced by streptomycetes isolated from soil, and with chitinases being used as defense enzymes by plants and animals. The antifungal actions to be discussed here, of the very specific polyoxins and nikkomycins and of purified chitinases, are ample proof of the essential nature of chitin in fungal growth.

Journal ArticleDOI
TL;DR: In this paper, the adsorption of Cu2+ on the chitin surface has been studied in seawater as a function of pH, temperature, and salinity.

Journal ArticleDOI
TL;DR: In this article, WGA-colloidal gold conjugates were used to locate chitin oligomers within fungal structures produced in vitro on Formvar plastic membranes, and during infection of susceptible French bean tissue.

Journal ArticleDOI
TL;DR: It was demonstrated that fragments arising from the action of chitinase provided a better substrate than crystalline chitIn for the deacetylase, and may play a multiple role in host-pathogen interaction.

Journal ArticleDOI
01 Jan 1990-Biomass
TL;DR: Nineteen strains of bacteria representing 39 genera and one yeast were screened for ability to hydrolyze chitin and the highest ratios were observed for strains in the genera: Bacillus and Serratia, followed by Micrococcus, Aeromonas, Vibrio, Clostridium and Plesiomonas.

Journal ArticleDOI
TL;DR: A mutualistic symbiosis of F. candida with chitinolytic microorganisms is likely to enhance chitin degradation, which is not only intra-intestinal but also involves an extra-intestinal phase.
Abstract: The relationship between Folsomia candida and chitin-degrading microorganisms was studied. On chitin agar, 1010 bacteria were isolated per g faeces, and 3.8×1011 bacteria per g gut contents, 1/3 of them showing a clear (chitin-free) zone around the colony. The most abundant chitin-degrading bacteria were Xanthomonas maltophilia and Curtobacterium sp. To determine the bacterial contribution in the use of chitin by F. candida, a feeding experiment was carried out. F. candida were fed with chitin, either amended with or without tetracycline as an inhibitor of bacteria. When tetracycline was omitted the biomass of F. candida was increased compared to those fed chitin with tetracycline. However, this result was observed only when the food replacement intervals were long enough to allow bacterial colonization before ingestion of the food. In a food-selection experiment, a preference for chitin colonized with microorganisms as opposed to sterile chitin was found. The results indicate that a mutualistic symbiosis of F. candida with chitinolytic microorganisms is likely to enhance chitin degradation. This relationship is not only intra-intestinal but also involves an extra-intestinal phase.

Patent
19 Oct 1990
TL;DR: In this paper, a modified cellulose and chitin for biocompatible dialysis membranes having a structure represented by the formula ##STR1## wherein Cell is cellulose or Chitin, in each case without hydroxyl groups, s=3 in the case of cellulose, and s=2 in a case of chitins, X denotes specified functional groups, R" is H or R, Z corresponds to the following groups of atoms: SR", SO3 H and salts thereof, SO-R, SONR"2, SO2 -
Abstract: A modified cellulose and/or chitin for biocompatible dialysis membranes having a structure represented by the formula ##STR1## wherein Cell is cellulose or chitin, in each case without hydroxyl groups, s=3 in the case of cellulose and s=2 in the case of chitin, R' is CH3 and/or C2 H5 and/or C3 H7, X denotes specified functional groups, R" is H or R, Z corresponds to the following groups of atoms: SR", SO3 H and salts thereof, SO-R, SONR"2, SO2 -R, SO2 NR"2, SO2 H and salts thereof, F, Cl, Br, I, NR"2, PR"2, PO3 H2 and salts thereof, PO2 H(OR), PO(OR)2, PO2 HR" and salts thereof, POR"(OR) and POR"2, x+t=0.75 to 2.85, t=0 to 2.85, x=0 to 2.85, and z=0.01 to 0.45. A process for preparation of the cellulose and/or chitin derivatives is also disclosed.

Journal ArticleDOI
TL;DR: In this paper, the main compounds were glycolic, lactic, 2-hydroxybutanoic, 3-deoxypentonic, xyloisosaccharinic, and 3,4,5-trideoxyheptaric acids from xylan.

01 Jan 1990
TL;DR: A wild-type strain of the fungus Aphanocladium album was mutagenized by UV irradiation in order to obtain chitinase-overproducing mutants, believed to be the first report on the induction of stable chit inase- overproducing mutants in a filamentous fungus.
Abstract: A wild-* strain of the fungus Aphanocladium album was mutagenized by UV irradiation in order to obtain chitinase-overproducing mutants. Mutants were screened on agar medium containing colloidal chitin and selected for their ability to produce large clearing zones around the colonies. Two mutant strains, designated E3 and E12, showed respectively a 26- and a 2.5-fold increase in maximal extracellular chitinase activity, determined in liquid medium with crystalline chitin as sole carbon source, compared to the wild-type strain. This is believed to be the first report on the induction of stable chitinase-overproducing mutants in a filamentous fungus. Regulation of enzyme activity was investigated in mutant E3 and the wild-type strain.

Journal ArticleDOI
TL;DR: In this article, a wild-type strain of the fungus Aphanocladium album was mutagenized by UV irradiation in order to obtain chitinase-overproducing mutants.
Abstract: Summary: A wild-type strain of the fungus Aphanocladium album was mutagenized by UV irradiation in order to obtain chitinase-overproducing mutants. Mutants were screened on agar medium containing colloidal chitin and selected for their ability to produce large clearing zones around the colonies. Two mutant strains, designated E3 and E12, showed respectively a 26- and a 2·5-fold increase in maximal extracellular chitinase activity, determined in liquid medium with crystalline chitin as sole carbon source, compared to the wild-type strain. This is believed to be the first report on the induction of stable chitinase-overproducing mutants in a filamentous fungus. Regulation of enzyme activity was investigated in mutant E3 and the wild-type strain.

Journal ArticleDOI
TL;DR: Chitin derivatives include chi tosan, N-acetylchitosan, monoacetyl chitin, dibutyrylchitin this article, chitosin butyrate, chito-san citrate, and chito -citrate.
Abstract: Chemical modification of chitin led to a series of derivatives: chi tosan, N-acetylchitosan, monoacetylchitin, dibutyrylchitin, chitosan acetate, chitosan butyrate, chitosan citrate and chitosan-po...