Showing papers on "Chitin published in 1973"

The chitin system

Abstract: SUMMARY 1The view is supported that chitin is not found in Deuterostomia because of the absence of chitin synthetase, and is not found in higher plants because of the absence of glucosamine. In Fungi, control mechanisms are present affecting the synthesis of glucosamine; chitin is often present, but when it is absent this probably results from a failure to synthesize glucosamine. 2A review of conformation maps for cellulose and chitin indicates the possibility of a slightly right-handed twist in small groups of chitin chains. 3The occurrence of α, β and γ-forms of chitin in the peritrophic membranes of various insects is described. Gamma chitin seems to be the commonest form. 4In several beetles, optical and electron-microscope studies trace the formation of chitinous cocoon fibres from larval peritrophic membrane and define the discrete ribbon-like nature of the, β chitin produced in the mid-gut. 5By studying apodemes it is found that orthopteroid insects are most varied, different molecular structures being present in levator, depressor and pretarsal tendons. By contrast, Hymenoptera and Coleoptera show very similar structures in all three apodemes as well as in other parts of the cuticle. Apodemes are regarded as sampling the cuticle at their varying points of origin; they provide especially favour able material for diffraction studies. 6In arthropod cuticles there is evidence for the widespread occurrence of α chitin micelles which are three chains thick in the direction of the c axis. This is compared with the structure of γ chitin where the chains repeat in groups of three along the c axis. 7Changes in the diffraction pattern are related to the series of proteins defined by Hackman. The chitin-protein complex is not affected by water or neutral salt extrac tion, but is disrupted by treatment in urea. 8Electron microscopy defines the unit of structure as a composite microfibril: a core of chitin surrounded by adsorbed proteins. This consists of ‘primary’ protein (often repeating as regular units along the fibrils) and a quantity of ‘satellite’ protein which obscures the imaging of the regularly arranged ‘primary’ protein. There are apparent ‘bridges' between the microfibrils. 9New diffraction data give information about the size and arrangement of micro-fibrils. These fibrils may be arranged in layers of ‘rods’, or as an hexagonal arrange ment of ‘rods’.

Natural chelating polymers : alginic acid, chitin, and chitosan

Abstract: Natural chelating polymers: alginic acid, chitin, and chitosan , Natural chelating polymers: alginic acid, chitin, and chitosan , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

A new insecticide inhibits chitin synthesis.

Abstract: Mos t of t he m e t h o d s t r ied so far are based on ion exchange, adsorp t ion , prec ip i ta t ion , and so lven t ex t rac t ion , b u t none seems l ikely to s a t i s fy t he above r equ i r emen t s . We h a d t he idea t h a t mic roo rgan i sms possess m a n y of the requi red proper t ies : se lec t iv i ty for b ind ing u r an i um, easy and inexpens ive p roduc t ion of t he b iomass , o p t i m u m degree of d ispers ion for fas t b ind ing kinet ics , and no was te problems. F r o m theore t ica l cons idera t ions and technological calcula t ions we devised a b a t c h process us ing cu l tu red algae exposed to f lowing sea water . For our e x p e r i m e n t s we used unicel lu lar green algae, m u t a t e d , selected, t e s t ed and cu l t iva t ed in l abora to ry exper imen t s . I n some cu l tures the m e d i u m was enr iched b y add i ng u r a n i u m sa l t in order to d e m o n s t r a t e t h a t even h i gh concen t ra t ions of u r a n i u m are no t po isonous to t he m u t a n t s . I n some experim e n t s a low e n r i c h m e n t was used for ana ly t ica l convenience . Some resu l t s are p re sen t ed in Tab le 1. A New Insecticide Inhibits Chitin Synthesis

Release of protoplasts from schizophyllum-commune by combined action of purified alpha-1, 3-glucanase and chitinase derived from trichoderma-viride

Abstract: Summary: Protoplast release from young mycelium of Schizophyllum commune by a lytic enzyme preparation from Trichoderma viride was accompanied by degradation of the three wall polymers, s-glucan, r-glucan and chitin. Part of the s-glucan was resistant. The resistance of s-glucan to enzymatic degradation increased with culture age and concomitantly the yield of protoplasts was reduced. Isolated s-glucan was also partly resistant to degradation, probably due to its crystallinity. In living cells s-glucan protected chitin and possibly r-glucan against degradation by external enzymes. s-glucanase, r-glucanase, chitinase and exo-laminarinase were purified from the Trichoderma enzyme mixture. Addition of only s-glucanase and chitinase was essential for protoplast release; r-glucan was degraded endogenously.

Chitosanase, a Novel Enzyme

Abstract: CHITIN is a structural polysaccharide composed of β(1→4) linked N-acetyl-D-glucosamine residues, found widely in exoskeletons of animals and in cell walls of green algae and fungi1,2. Chitosan is a partially deacetylated form of chitin2; those commercially available have an average degree of acetylation of 10–30% and are prepared by treating chitin with concentrated alkali at high temperature. Chitosan also occurs naturally in different degrees of acetylation, often in close association with chitin. A mainly deacetylated form is a major component of the zygomycete fungal cell wall3 while chitins showing a 10% deacetylated but poorly defined fraction have also been found in squid pen, lobster, crab and Rhodnius4,5. The chitosan complex is probably a widely occurring structural polymer. Other modifications of the chitin polymer exist as essential components of bacterial cell walls. In some bacteria, alternate N-acetylglucosamine units are substituted at C3 (peptidoglycan), and these are susceptible to lysozyme; in others, a modification occurs in which many of the NAc glucosamine units have lost their acetyl groups. Egg white lysozyme will not attack this naturally occurring de-N-acetylated mucopeptide6.

Solvents for and purification of chitin

Abstract: New solvents for chitin comprising dimethylacetamide, N-methylpyrrolidone or mixtures of these in combination with a minor proportion of lithium chloride, and their use in the purification of chitin for regeneration in the form of films and fibers are described.

Chitinase activity in Lycopersicon esculentum and its relationship to the in vivo lysis of Verticillium albo-atrum mycelium

Abstract: Healthy and Verticillium albo-atrum -infected tomato plants were shown to possess a constitutive enzyme capable of hydrolysing chitin of N -acetylglucosamine. It was present in leaf, stem and root tissue extracts, vacuum extracted xylem sap and to a lesser extent in the bleeding exudate. The partially purified enzyme showed optimal activity between pH 5·4 and 5·8 and at a temperature of 28°C. The K m and V max values for chitin were 0·408 mg/ml and 3·7 μg N -acetylglucosamine N/h ml respectively. No free hexosamines were detected in healthy or diseased plants. Authentic lysozyme and β-glucosidase showed slight chitinase activity. Only trace amounts of lysozyme activity could be detected in tissue extracts. Crude extracts possessed high β-glucosidase and low chitinase activities; after partial purification the β-glucosidase activity was negligible while chitinase activity increased tenfold. Chitinases from Streptomyces and V. albo-atrum and the tomato enzyme responded identically to selected inhibitors. Inoculation of tomato cultivars with isolates of V. albo-atrum from hop and tomato gave a range of disease expression from susceptible to resistant. Infection resulted in a significant increase in chitinase activity which was greater in the susceptible reaction. The apparent pH of xylem exudate from diseased plants (6·8 to 7·1) was too high for appreciable enzyme activity. The activity of host polysaccharases is discussed in relation to the well-documented in vivo lysis of plant pathogens.

Process for facilitating wound healing with N-acetylated partially depolymerized chitin materials

Abstract: Wound healing compositions and the process of healing wounds with such compositions are described, the compositions containing chitin, partially depolymerized chitin or a chitin derivative.

Adsorption and reactions of chitinase and lysozyme on chitin.

Abstract: Isotherms for adsorption of chitinase on chitin and lysozyme on chitin have been determined at two temperatures and rates of hydrolysis of chitin catalysed by these enzymes have been measured at three temperatures and at several enzyme concentrations for each. Ribonuclease, not an enzyme for chitin, and heat-denatured lysozyme and chitinase show reduced or no adsorption to this substrate. Initial hydrolysis rates of chitin by both enzymes are proportional to total enzyme concentrations in the range of concentrations studied. These kinetics cannot, however, be related to the adsorption isotherms because of the non-equilibrium nature of the isotherms.

Chitin Coated Cellulose as an Adsorbent of lysozyme like Enzymes Preparation and Properties

Abstract: As a new adsorbent of lysozyme-like enzymes, chitin coated (CC-)cellulose was prepared. CC-cellulose was stable and had good flow properties for use in column chromatography. Affinity chromatography with CC-cellulose showed that 3~5 mg of lysozyme/ml resin was adsorbed specifically and desorbed quantitatively under mild conditions. The utilities of the method of affinity chromatography with CC-cellulose are discussed.

Purification of chitin

Abstract: New solvents for chitin have been discovered comprising a 1, 2chloroalcohol in admixture with an acidic solvent, particularly a mineral acid, and a method for purifying the chitin and regenerating it from solution in the form of powdered chitin and/or crystalline fibrils.

Role of acetylglucosamine in chitin synthesis in crayfish—II. Enzymes in the epidermis for incorporation of acetylglucosamine into UDP-acetylglucosamine

Abstract: 1. 1. Activity of an enzyme which phosphorylates acetyglucosamine has been found in the epidermis of crayfish. This activity does not appear to be competitively inhibited by glucose. 2. 2. A quantitative assay based on area of epidermis was developed for UDP-acetylglucosamine pyrophosphorylase. The activity of this enzyme was correlated with the stages of the molting cycle. 3. 3. UDP-acetylglucosamine pyrophosphorylase activity was low during intermolt but increased early in premolt and declined in postmolt. 4. 4. These data are discussed in terms of the onset of premolt chitin synthesis and the precursor to premolt chitin synthesis.

Observations on regenerated chitin films

Abstract: Chitin films regenerated from shrimp shell waste were studied in order to determine stress-strain behaviour and tensile strengths as related to preferential chain orientation.

Chitinolysis by Serratiae Including Serratia liquefaciens (Enterobacter liquefaciens)

Abstract: Forty-six strains of serratiae, including 10 strains of Serratia liquefaciens (syn.: Enterobacter liquefaciens) hydrolyzed chitin in a chitin-salts-Casamino Acids agar medium. Strains which were tested on chitin-salts agar were able to use chitin as a sole source of carbon, nitrogen, and energy. None of the other members of the family Enterobacteriaceae studied produced chitinase. The ability to hydrolyze chitin may be a useful characteristic in differentiating serratiae from other Enterobacteriaceae. However, many more strains will have to be tested for chitinase synthesis before the usefulness of the test can be determined.

Method of isolation of lysozyme

Abstract: Lysozyme from human, avian, non-human mammalian, and vegatable sources is isolated from said sources and provided in a high degree of purity by adsorbing the lysozyme upon chitin obtained from Loligo vulgaris by contacting said chitin with an acidic aqueous suspension of the crude lysozyme containing material, and eluting the pure lysozyme from said chitin with aqueous acid.

Chitin Coated Cellulose as an Adsorbent of Lysozyme-like Enzymes: Some Applications

Abstract: In the previous paper,1) chitin coated (CC-)cellulose* was shown to be a good adsorbent of lysozyme. Hen egg white lysozyme was adsorbed firmly at pH 8 and 1M NaCl and desorbed quantitatively with 0.1 at acetic acid. Lysozyme was isolated from hen egg white with CC-cellulose column chromatography and the purity of the lysozyme thus isolated was 95%. Isolation of lysozyme-like nzymes with CC-cellulose column chromatography was as follows. Each sample solution was made pH 8 and 1M in NaCl. About 6.5ml of CC-cellulose quilibrated with the starting buffer (0.1M phosphate buffer (pH 8) containing 1M NaCl) was added to the filtered sample solution. After the suspension was stirred for 20min, the resin was collected with filtration and packed in a column (1•~8cm) using the starting buffer. The column was eluted first with about 30ml of the starting buffer and then with 0.1M acetic acid. The flow rate was ca. 10ml/hr for the starting buffer elution and ca. 3ml/hr for 0.1M acetic acid elution. All procedures were performed at room temperature (10•`20•Ž). New resin was used for each run. All protein concentrations were determined by ab sorption at 280nm. Chitinase and lytic activities were measured as described in the previous paper,1) and were expressed in relative activities (%) to crystal line hen egg white lysozyme. Twenty fiveml of saliva was dilute with 25ml of 0.1M phosphate buffer (pH 8) and lysozyme-like enzymes were isolated as described above. The result of chromatography is shown in Fig. 1-a. The absorption spectrum of #13 was quite different from that of #2 and it is obvious that the protein composition in the first peak is different from the second peak. The second peak showed considerable activity toward glycol chitin and minor activity toward bacterial sub strate. On the other hand, #2 did not show any activity toward glycol chitin or bacterial substrate. Thus a small amount of lysozyme-like enzyme was isolated from saliva. This enzyme could be lysozyme owing to its lytic activity and it has more activity toward glycol chitin than toward bacterial substrate.

Hydrolysis of glycol chitin by an endo-and exo-type of beta-N-acetylglucosaminidase from human parotid saliva.

Abstract: Since it was shown that chitin, a polymer of N-acetyl-p-D-glucosaminide bounded by 1,4 linkages, could be lysed by egg white lysozyme (BERCER and WEISER, Biochim Biophys Acta 26: 517, 1957), the so-called lysozyme (EC 3.2.1.17) is considered to be an endo-type of ps-N-acetylglucosaminidase (NAGase). More recently, an exo-type of NAGase (EC 3.2.1.30) from human parotid saliva was purified successfully (WATANABE ET AL, J Dent Res 52: 782-790, 1973) . In a preliminary study, we confirmed that the exotype of NAGase hydrolyzes the chitin oligosaccharides (dimers, trimers, and tetramers of Nacetyl-3-glucosaminide).a The purpose of this study was to observe the hydrolysis of chitin through the synergistic effect of the endoand exo-type of NAGase from human parotid saliva. Hydrolysis experiments were carried out by a modification of the methods of Hamaguchi et al (J Biochem (Tokyo) 48: 351, 1960). The reaction mixture contained 10 mg glycol chitin,5 16 ,ug purified endo-type of NAGase from human parotid saliva (IWAMOTO ET AL, J Dent Res 49: 1104, 1970), 8 ,ug purified exo-type of human parotid NAGase in 0.05 M citrate-0.1 M phosphate buffer (pH, 4.5) in a final volume of 1 ml and a drop of toluene to inhibit bacterial growth. After incubation for 4, 8, or 16 hours at 37 C, the liberated N-acetylglucosamine was measured by the methods of Reissig et al (J Biol Chem 217: 959, 1955) . Optical density readings were made with a spectrophotometere at 585 nm, against a blank that contained all components except enzyme. As indicated in the illustration, glycol chitin was hydrolyzed by the endo-type of NAGase gradually, whereas the exo-type did not hydrolyze it at all. In a system that contained the endoand exo-type of NAGase, initially the hydrolysis of the glycol chitin increased. After 16 hours incubation, liberated N-acetylglucosamine concen-

Effects of Some Polysaccharide Sulfates and Some Phosphates on Neutral Proteases and Plasminogen Activators

Abstract: Several polysaccharide sulfates (heparin, dextran sulfate, chitin disulfate, cellulose sulfate) and some phosphates (α-tocopherol phosphate, polyphloretin phosphate, hexametaphosphate) were investigat