Showing papers on "Chitin published in 1975"

Powdered chitin agar as a selective medium for enumeration of actinomycetes in water and soil.

Abstract: Agar media made with 0.4% colloidal chitin plus mineral salts and adjusted to pH 8.0 was superior to four other commonly used media for the isolation and enumeration of actinomycetes from water samples. More actinomycetes developed on chitin agar, and the development of bacteria and fungi was suppressed. Frozen and vacuum-dried chitin from aqueous colloidal suspensions was finely divided and gave results comparable to those obtained with media prepared from colloidal suspensions. Images

Inhibition of fungal growth by wheat germ agglutinin

Abstract: GROWTH of fungal hyphae is the result of a complex and poorly understood process of cell wall synthesis and extension, that is restricted to the hyphal apex1–3. In fungi with chitin–glucan hyphal walls, such as the Deuteromycetes Trichoderma viride and Fusarium solani1, hyphal extension and septa formation involve the synthesis of chitin in hyphal tips and septa4. We therefore studied the effect on such fungi of wheat germ agglutinin (WGA), a lectin which interacts specifically with chitin oligomers5,6.

Adsorption of Vibrio parahaemolyticus onto Chitin and Copepods

Abstract: Vibrio parahaemolyticus was observed to adsorb onto chitin particles and copepods. The efficiency of adsorption was found to be dependent on pH and on the concentration of NaC1 and other ions found in seawater. Highest efficiency was observed in water samples collected from Chesapeake Bay and lowest in water from the open sea. V. parahaemolyticus was found to adborb onto chitin with the highest efficiency of the several bacterial strains tested. Escherichia coli and Pseudomonas fluorescens did not adsorb onto chitin. The adsorption effect is considered to be one of the major factors determining the distribution of this species and affecting the annual cycle of V. parahaemolyticus in the estuarine system.

Chitin synthetase zymogen is attached to the yeast plasma membrane.

Abstract: Pretreatment of yeast protoplasts with concanavalin A, according to the method used by G. A. Scarborough for Neurospora (J. Biol. Chem. 250, 1106-1111, 1975), reinforced the plasma membranes, and helped to maintain their integrity during subsequent lysis of the protoplasts. After purification by centrifuging on a Renografin density gradient, practically intact membranes were obtained. Previous labeling of the protoplasts with 125I or with [3H]concanavalin A resulted in recovery of the radioactivity in the membrane fraction. The bulk of the chitin synthetase (chitin synthase; UDP-2-acetamido-2-deoxy-D-glucose:chitin 4-beta-acetamidodeoxyglucosyltransferase; EC 2.4.1.16) recovered in the gradient was also found In this fraction; in the zymogen form. About 20% of the activity sedimented in a plasma-membrane-free fraction at lower density. Glutaraldehyde inactivated chitin synthetase when it was added to a lysate, but not when applied to intact protoplasts. It is concluded that chitin synthetase is so oriented in the membrane that it is only accessible from the inside of the cell. These results confirm our previous hypothesis that the chitin synthetase zymogen is associated with the plasma membrane, a basic assumption for the explanation of localized activation of the enzyme and initiation of septum formation.

A pathway of chitosan formation in Mucor rouxii. Enzymatic deacetylation of chitin.

Abstract: 1. An enzyme that catalyzes hydrolysis of acetamido groups of chitin derivatives was found in the supernatant fraction of Mucor rouxii. 2. Partially O-hydroxyethylated chitin (glycol chitin) was used as a substrate in the purification and characterization of this enzyme. A 140-fold purification was obtained by means of ammonium sulfate fractionation followed by chromatography on carboxymethylcellulose and DEAE-cellulose. 3. The enzyme releases about 30% of the acetyl groups of glycol chitin, giving a product with a decreased sensitivity to lysozyme. The enzyme also deacetylates chitin and N-acetylchitooligoses, whereas it is inactive toward bacterial cell wall peptidoglycan, N-acetylated heparin, a polymer of N-acetylgalactosamine, di-N-acetylchitobiose and monomeric N-acetylglucosamine derivatives. 4. This enzyme shows a pH optimum of 5.5. The Km value for glycol chitin is 0.87 g/l or 2.6 mM with respect to monosaccharide residues. 5. The occurrence of this enzyme accounts for the formation of chitosan in fungi.

Timing and function of chitin synthesis in yeast.

Abstract: A temperature-sensitive mutant of Saccharomyces cerevisiae, L-2-42, is blocked at 37 C at a stage of the cell cycle prior to septum formation. When single cells of the mutant are allowed to bud at 37 C in a medium containing tritiated glucose, a large incorporation of radioactivity into chitin takes place. Thus, the synthesis of chitin, the major component of the primary septum, is initiated in a phase of the cell cycle which precedes septum closure. This early period of chitin synthesis is not required for emergence and growth of buds because, in the wild type, budding takes place normally in the presence of concentrations of polyoxin D that effectively and specifically prevent chitin formation. However, at a later time a majority of these cells lyse, presumably because of the inability to form a septum. Polyoxin D also prevents the appearance of enhanced fluorescence at the junction between mother cell and bud, as observed in the presence of a brightener. Therefore, the fluorescence is due to chitin and its presence at the base of very early buds indicates that chitin synthesis begins at or shortly after bud emergence. A scheme for chitin synthesis and primary septum formation which embodies these and other results is presented.

Microfibril assembly by granules of chitin synthetase

Abstract: Purified preparations of chitin synthetase (EC 2.4.1.16; UDP-2-acetamido-2-deoxy-D-glucose:chitin 4-beta-acetamidodeoxyglucosyltransferase), capable of forming microfibrils in vitro, were isolated from yeast cells of Mucor rouxii. Chitin synthetase was obtained either by substrate-induced liberation of bound enzyme (54,000 x g pellet) or by isolation of unbound enzyme present in the 54,000 x g supernatant of a cell-free extract. Both preparations contained ellipsoidal granules from about 350 to 1000 A diameter. Many granules exhibited a marked depression. No typical unit membrane profiles appeared in thin sections of glutaraldehyde/OsO4-fixed samples. Upon incubation with substrate and activators, chitin microfibrils were produced. The microfibrils were often found intimately associated with granules. The most common configurations were: a microfibril with a granule at one end, or two microfibrils "arising" from the same granule. These findings lend support to the granule hypothesis for the elaboration of cell wall microfibrils by end-synthesis.

Properties of Chitin Synthetase from Coprinus cinereus

Abstract: SUMMARY: Preparations of chitin synthetase (EC. 2.4.1.16) from the stipe of the toadstool Coprinus cinereus were characterized. Microsomal fractions had a very high specific activity. The chitin synthetase had been solubilized by treatment with digitonin, with an increase in specific activity and in stability. Optimum conditions for enzyme activity were determined. These preparations needed only a divalent cation and UDP-N-acetylglucosamine for chitin synthesis and showed no primer requirement. The sole glycosyl product was characterized as macro-molecular chitin.

Lactase and other enzymes bound to chitin with glutaraldehyde

Abstract: Acid tolerant lactase (I), α-chymotrypsin (II), and acid phosphatase (III) were immobilized on chitin with glutaraldehyde. Pretreatments of the chit in with acid, alkali, ammonia, and pronase were compared with respect to release of titratable amino groups and ability to retain lactase activity. Shrimp chitin appeared to be more sensitive to pretreatment conditions and so effort was concentrated on crab. An acid-alkali pretreatment was selected as most practical and economical, and the properties of enzymes fixed on crab chitin were studied intensively. The pH optima of the fixed enzymes were shifted about one pH unit; the shift for I was toward more acid pH, for II was toward alkaline pH, and for III was toward acid pH. The retained activity of immobilized I was approximately 60% that of the native enzyme. A column in continuous operation with I on chitin-glutaraldehyde gave an apparent activity half-life of 27 days.

Chemical analysis of cell wall regeneration and reversion of protoplasts from Schizophyllum commune.

Abstract: In the presence of MgSO4 as osmotic stabilizer, nucleated protoplasts of Schizophyllum commune developed a large vacuole and could be isolated on the basis of their low buoyant density. All these protoplasts were capable of wall regeneration and about 50 percent reverted to the hyphal mode of growth in liquid medium. The kinetics of the formation of three main cell-wall components, S-glucan (α-1,3-glucan), R-glucan (β-1,3, β-1,6-glucan) and chitin were studied from the onset of regeneration. S-glucan and chitin accumulation as well as RNA and protein synthesis started simultaneously after a short lag, but R-glucan formation was delayed. The reversion to hyphal tubes only began after several hours of rapid R-glucan synthesis. Cycloheximide (0.5 μg/ml), inhibiting protein synthesis by 98% inhibited the formation of R-glucan and the reversion to hyphal growth but the formation of chitin and S-glucan did start and continued seemingly unimpaired for several hours. This indicates that the enzymes responsible for the synthesis of S-glucan and chitin remained intact during protoplast preparation. Polyoxin D inhibited both the synthesis of chitin and R-glucan and also the reversion to hyphal growth. However, the synthesis of S-glucan was not suppressed. These inhibitor studies as well as the kinetics of R-glucan formation during normal regeneration suggest that the synthesis of R-glucan is required for the initiation of hyphal morphogenesis.

A Kinetic Study of a Solubilized Chitin Synthetase Preparation from Coprinus cinereus

Abstract: SUMMARY: The solubilized chitin synthetase preparation from the stipes of Coprinus cinereus is activated by its substrate, UDP-N-acetylglucosamine, and by carbohydrates, in particular N-acetylglucosamine, diacetylchitobiose and glucose. Analysis of the results of variation in enzyme activity with UDP-GlcNAc concentration by several methods suggested that this substrate is an allosteric activator, with Hill coefficients close to 2 and 4 at concentrations above and below 0.1 mM respectively, and an [S]0.5 value of 0.9 mM. N-acetylglucosamine lessened but did not abolish the sigmoidal shape of the velocity-substrate concentration plot. The chitin synthetase was inhibited by adenine and uridine nucleotides, and uridine diphosphate was a powerful competitive inhibitor. The enzyme preparation also contained a nucleoside diphosphatase activity and the implications of the removal of the inhibitory UDP formed by the chitin synthetase are considered.

Chitin films and fibers

Abstract: A new method for producing high-strength films, fibers and other shaped articles from chitin has been discovered, whereby an anhydrous solution of chitin is made into the desired shape, the chitin is insolubilized with an organic non-solvent for the chitin and the resultant shaped article, if desired, is oriented, by cold drawing until its properties, such as tensile strength, are substantially enhanced. The films, fibers, and other shaped articles capable of being oriented or in oriented form, are novel and useful in such applications as food wrap and surgical sutures.

Studiesin vivo andin vitro on chitin synthesis during the larval-adult moulting cycle of the migratory locust,Locusta migratoria L.

Abstract: 1. Chitin synthesis inLocusta migratoria has been examined by following the incorporation of labelled N-acetylglucosamine into chitin at different stages of the larvaladult moulting cycle from 4 days before to 8 days after ecdysis. With glucose high incorporation rates were measured only during the first 2 days after ecdysis. Acetylglucosamine was incorporated intensively before this period (5 to 7 times higher than glucose). After ecdysis the rate of aminosugar incorporation increases rapidly up to the level of maximum incorporation of glucose and remains at this level for one week. 2. During the days prior to imaginal ecdysis the precursors for chitin synthesis originate almost exclusively from the decomposition of the chitin of the larval cuticle. 3. A few minutes after injection of labelled glucose, acetylglucosamine, or UDP-acetylglucosamine into 24 hour adult locusts, radioactivity is detectable in all chitin precursors. These compounds are found mainly in the integument and in the hemolymph, and to a lesser extent also in the fat body. 4. Preparations of the abdominal integument incorporate chitin precursorsin vitro; under these conditions glucose is the preferred precursor.

Chitin complexes with alcohols and carbonyl compounds

Abstract: New compositions of matter comprising complexes of chitin with lower molecular weight alcohols, aldehydes and ketones have been discovered. These complexes are useful in the solution and purification of chitin and in the preparation of modified chitins for fibers, films and plastics, and for pharmaceutical purposes.

Chemical and structural differences in mycelial and regeneration walls of trichoderma viride.

Abstract: When incubated in Winge medium, protoplasts from Trichoderma viride obtained by treatment with Micromonospora chalcea or Streptomyces venezuelae RA lytic systems first synthesized an aberrant wall, different from the normal one; it was aseptate, larger and irregular in size and length. They then regenerated a new wall, similar to the original one from which they were liberated. Analysis showed that the wall polymers were mainly beta-(1-3) glucan, beta-(1-6) glucan and chitin in the normal walls, whereas chitin was absent in aberrant tubes. These results are discussed below together with electron micrographs of aberrant and normal walls.

Use of chitin derivatives in automobile products

Abstract: A method of using chitin derivatives as defoggers for clear surfaces and as deodorizers is disclosed.

Composition of cellulin, the unique chitin-glucan granules of the fungus, Apodachlya sp.

Abstract: Cellulin granules, the polysaccharide inclusions found uniquely in oomycetous fungi of the order Leptomitales, were isolated from Apodachyla sp. The granules were prepared free of cell wall and cytoplasmic contaminants. Biochemical analyses and X-ray diffraction studies demonstrated that the granules were composed of 60% chitin and 39% glucan consisting of beta-1,3- and beta-1,6-linked glucose units. A protein content of only 0.1% was attributed to an insignificant amount of cytoplasmic contamination. Isolated granules and those in situ showed no apparent differences in their microscopic form.

Biosynthesis of chitin by particulate fractions from Cunnighamella elegans.

Abstract: The enzyme chitin synthetase (UDP-acetylaminodeoxyglucosyl transferase, EC 2.4.1.16) in Cunninghamella elegans has been investigated. The enzyme was present in the microsomal, cell wall, mitochondrial and the soluble cytoplasmic fraction of the mycelium, with the former having the highest specific activity. The properties of the enzyme in this fraction were investigated; the Km for UDP GlcNAc was 1.23 mM and 2.08 mM GlcNAc in the presence of 1 mM UDP GlcNAc. The temperature optimum was between 26 degrees and 29 degrees C and maximal activity was at pH 6.25. Mg++ ions had no effect on chitin synthesis, but soluble chitodextrins inhibited the enzyme. The production of chitin synthetase was correlated with the growth of the fungus, maximum activity being found during the late exponential phase of growth. Chitin was confirmed as the sole product of enzyme action, by digestion with chitinase.

Chitin as an extender and filter for tobacco

Abstract: Chitin, either as such or in toasted form, has been found to be an effective extender and filter for tobacco. It can be used in substantial amounts with tobacco blends without adversely affecting such physical properties as packing ability, burning rate or retention of ash. Organoleptic properties such as aroma, taste and smoothness are little affected. To the degree that chitin is used in the mixture, nicotine and noxious tars are reduced. Mixtures of chitin and tobacco represent new compositions.

The structure of chitin and chitosan

Abstract: The short range atomic arrangements in crystalline chitin, crystalline chitosan and amorphous chitosan films are shown to be similar in that the fundamental rings and chains are retained in all of these structures. The interchain bonding differs, however, and is weakest in amorphous chitosan and strongest in crystalline chitin.

The Structural Macromolecules

Abstract: Chitin is the most abundant organic skeletal component of invertebrates. It is the characteristic polysaccharide of several major phyla (Arthropoda, Annelida, Mollusca, and Coelenterata) and also functionally replaces cellulose in many fungi. It has been estimated that the Copepoda alone may synthesize 109 tons of chitin annually, in comparison with the calculated total world-wide production of 1011 tons of cellulose (Tracey, 1957). In arthropods chitin is never found free of protein.

Method of enzyme immobilization

Abstract: PURPOSE: Method of immobilizing enzymes in relatively low cost by using deacetylated chitin as support. COPYRIGHT: (C)1977,JPO&Japio

[The chemistry of a chitin-protein from crayfish (Astacus fluviatilis) (author's transl)].

Abstract: A chitin-protein complex is obtained from crayfish (Astacus fluviatilis) by gentle decalcification with acetic acid and EDTA. The complex is treated with lithium rhodanide, urea, anhydrous formic acid, pronase, papain, anhydrous formamide or 1N NaOH. The first three of these substances have little or no effect on the stability of the chitin-protein complex. The enzymes remove most of the protein, and the last two reagents remove all of it. The protein remaining bound to the polysaccharide after treatment of the chitin-protein complex with pronase or papain is relatively rich in glycine. Quantitative analysis yielded values for the acetyl, glucosaminyl and amino acid residues which reproduce the composition of the corresponding chitin-protein complex. In these calculations however, allowance must be made for the fact that glucosamine is partly destroyed by the acid by hydrolysis and interferes with the determination of basic amino acids. The results of the present work suggest that the chitin in crayfish is present in the form of a stable complex with protein, possibly held together by covalent binding of the protein to the chitin, with glycine as the connecting amino acid.