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PubMed2006

Adsorption of Reactive Red 141 from wastewater onto modified chitin.

This research involved the adsorption of synthetic reactive dye wastewater (SRDW) by chitin modified by sodium hypochlorite and original chitin in batch experiments. The comparison of maximum adsorption capacity used the Langmuir model to describe SRDW adsorption onto chitin and modified chitin under a system pH of 11.0. Maximum dye adsorption by chitin increased from 133mgg(-1) to 167mgg(-1) at temperatures of 30-60 degrees C, respectively. For modified chitin, the capacity decreased from 124mgg(-1) to 59mgg(-1) when the temperature increased from 30 degrees C to 60 degrees C, respectively. Both Na(2)SO(4) and Na(2)CO(3) increased in dye adsorption. The spectra of attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectrometry confirmed the hydroxyl groups as functional groups of modified chitin, which affected the modification and the SRDW adsorption. The adsorbed dyes were eluted by distilled water and 1M NaOH to confirm the dye adsorption mechanism. Total elution of modified chitin and chitin were 92.76% and 55.29%, respectively. Although modified chitin had a maximum adsorption capacity less than chitin, elution of the dye from modified chitin was easier than chitin. Therefore, modified chitin could be suitable in a column system for dye pre-concentration as well as wastewater minimisation. In addition, the column study showed that modified chitin could be used for more than four cycles of adsorption and elution by distilled water.

Adsorption↗
PubMed1990

Inhibition by sulfated chitin derivatives of invasion through extracellular matrix and enzymatic degradation by metastatic melanoma cells.

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, heparin 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.

Binding, Competitive↗
PubMed1990

Detection of chitin deacetylase activity after polyacrylamide gel electrophoresis.

Mucor racemosus and Rhizopus nigricans were used as sources of chitin deacetylases. Crude protein extracts were subjected to polyacrylamide gel electrophoresis at pH 8.9 (Davis system) or 4.3 (Reisfeld system) under native conditions. After electrophoresis, an overlay gel containing 0.1% (w/v) glycol chitin as substrate was incubated in contact with the separation gel. Chitin deacetylase activity was revealed by uv illumination with a transilluminator after staining for 5 min in 0.01% (w/v) Calcofluor white M2R. Chitosan (deacetylated chitin) generated by chitin deacetylases appeared more fluorescent than the intact chitin embedded in the overlay gel. Chitosan in a separate overlay gel was also subjected to a nitrous acid treatment which specifically depolymerizes chitosan while leaving chitin intact. Hydrolysis of chitosan by nitrous acid followed by Calcofluor staining yielded dark (nonfluorescent) bands (chitin deacetylase activities) in the fluorescent chitin-containing gel. Both assays revealed the presence of several chitin deacetylases from Zygomycetes. The same assays were performed after denaturing electrophoresis in 12% (w/v) polyacrylamide gels containing 0.1% (w/v) glycol chitin. Enzymes were renatured in buffered 1% (v/v) purified Triton X-100. Chitin deacetylases with estimated molecular weights between 26,000 and 64,000 were detected after Calcofluor staining. The assays were also performed in two-dimensional gel electrophoretic systems. Chitin deacetylases can be rapidly revealed by using the assay involving the nitrous acid treatment. However, both assays (with and without nitrous acid treatment) should be run to conclusively demonstrate chitin deacetylase activity after polyacrylamide gel electrophoresis.

Amidohydrolases↗
PubMed2004

Saccharomyces cerevisiae Bni4p directs the formation of the chitin ring and also participates in the correct assembly of the septum structure.

In Saccharomyces cerevisiae cytokinesis is efficiently achieved when a concerted series of events take place at the neck region, leading to septum formation. Here it is shown that Bni4p plays a crucial role in this process. Deltabni4 mutants contain normal amounts of chitin and show normal chitin synthase III (CSIII) activity, but are partially resistant to Calcofluor White (CFW), probably due to the striking pattern of chitin distribution. CFW vital staining shows that chitin is synthesized in daughter cells and that it is also asymmetrically deposited at the mother-side of the neck in large-budded cells. This specific pattern coincides with that of Chs4p and Chs3p proteins. Alternatively, staining of unbudded cultures confirmed that Bni4p directs early chitin ring assembly, but is no longer required for the chitin deposition that occurs late in the cell cycle at cytokinesis. Consequently, this work provides a strategy to genetically discriminate between the absence of chitin synthesis (Deltachs3 mutant) and failure in chitin ring assembly (Deltabni4 mutants). The characterization of double mutants affected in chitin synthesis and primary septum (PS) assembly (Deltamyo1 and Deltachs2) provides evidence for the cooperation of Bni4p in PS formation besides its role in chitin ring assembly. In addition, it is shown that the chitin ring, but not the late deposition of chitin, cooperates in the correct assembly of the actomyosin ring and the PS when the biological function of the septins is compromised. We conclude that Bni4p is not only required for the assembly of the chitin ring, but is also involved in septum architecture and the maintenance of neck integrity.

Cell Cycle Proteins↗
PubMed2002

Localized delivery of paclitaxel in solid tumors from biodegradable chitin microparticle formulations.

Paclitaxel (Taxol)-containing chitin and chitin-Pluronic F-108 microparticles were formulated as biodegradable systems for localized administration in solid tumors. The microparticles were characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and swelling studies in phosphate-buffered saline (PBS, pH 7.4). Lysozyme-induced degradation and in vitro release of paclitaxel was examined in PBS at 37 degrees C. The percent change in tumor volume was used to assess efficacy of the Formulations after local administration in murine Lewis lung carcinoma model. FT-IR confirmed higher degree of acetylation in chitin microparticles from the starting chitosan sample and the SEM showed that the chitin-Pluronic F-108 microparticles were significantly more porous than chitin microparticles. Due to higher porosity, chitin-Pluronic microparticles were able to imbibe higher swelling medium and degraded much faster in the presence of lysozyme than chitin microparticles. After 48 h. 51% of incorporated paclitaxel was released from chitin-Pluronic microparticles as compared to 28% from chitin microparticles. In vivo studies in Lewis lung carcinoma-bearing mice showed that the tumor volumes after 6 days using paclitaxel-loaded chitin and chitin-Pluronic F-108 microparticles was 458 and 307 mm3, respectively. In contrast, the tumor volume was 997 mm3 for the untreated control. The results of this study show that chitin and chitin-Pluronic F-108 microparticles are biodegradable drug delivery systems that can be useful for localized delivery of paclitaxel in solid tumors.

Acetylglucosamine↗
PubMed1984

Immunological activity of chitin and its derivatives.

The effect of chitin and its derivatives on the activation of peritoneal macrophages in vivo, on the suppression of tumour growth in syngeneic mice and on the protection of the host against bacterial infection was examined. Thirty percent deacetylated chitin (30% DA-chitin), 70% DA-chitin and carboxymethyl-chitin (CM-chitin) induced cytotoxic macrophages most effectively. Chitosan, hydroxyethyl-chitin, dihydroxypropyl-chitin (DHP-chitin) and DHP-chitosan had moderate activities. Phosphorylated-, sulphonated- or acetyl-chitin, however, were less effective. Both 70% DA-chitin and DHP-chitosan were most active on the suppression of Meth-A tumour growth in BALB/c mice, and 30% DA-chitin had a moderate effect. For the stimulation of non-specific host resistance against Escherichia coli infection, 30% and 70% DA-chitin were effective.

Adjuvants, Immunologic↗
PubMed2003

In vitro effect of chitin particles on the innate cellular immune system of gilthead seabream (Sparus aurata L.).

The interaction between chitin particles and gilthead seabream (Sparus aurata L.) head-kidney leucocytes, as well as their effects on the main innate cellular immune responses were studied. Three different chitin particle-sizes were tested: unfiltered, <10 microM and >10 microM. Leucocytes were able to phagocytose only the chitin particles of <10 microM but not the >10 microM ones. Leucocytes were incubated with different concentrations (0 to 1000 microg ml(-1)) of the above chitin particles for 1, 4, 24 or 48 h and their effects on leucocyte viability and the innate cellular immune system were evaluated. Leucocytes incubated with chitin for 48 h maintained their viability as determined by the MTT viability test. Leucocyte phagocytosis of bacteria after chitin incubation for 1 or 4 h was enhanced by the highest chitin concentration tested of each of the chitin fractions studied, while the respiratory burst activity was unaffected. As regards leucocyte natural cytotoxic activity against tumour cells, prior incubation of leucocytes with chitin particles for 1 or 4 h increased while incubation for 24 or 48 h reduced the cytotoxic activity in a dose dependent manner. Statistically significant differences between the different chitin concentrations and between the three chitin particle-size fractions were detected. To conclude, gilthead seabream head-kidney leucocytes were able to phagocytose chitin particles smaller than 10 microM, and the main cellular innate immune activities were enhanced as a consequence of prior incubation with chitin particles.

Animals↗
PubMedDate not supplied

Preparation of C-6 substituted chitin derivatives under homogeneous conditions.

Tosylation of chitin under homogeneous conditions was achieved by the reaction of tosyl chloride with chitin in a DMAc/LiCl solvent system. The resultant tosyl-chitin was fully N-acetylated with acetic anhydride in methanol. The fully acetylated tosyl-chitin was subsequently reacted with the sodium salts of ethyl p-hydroxybenzoate, diethyl malonate, and diethyl phosphite in DMAc to give the corresponding chitin derivatives of 6-O-ethyl benzoate-chitin, 6-deoxy-diethyl malonate-chitin, and 6-(deoxydiethyl) phosphite-chitin, respectively. Subsequent hydrolysis of the chitin-ester derivatives with tert-butoxide in dimethyl sulfoxide (DMSO) generated 6-O-carboxyphenyl-chitin and 6-(deoxydicarboxy)methyl-chitin. The structures of the chitin derivatives were assessed by FT-IR, (13)C NMR, and (31)P NMR, while the degree of substitution of the S(N)2 reaction was estimated by elemental analysis. All the chitin derivatives were found to be soluble or swellable in water, DMAc, or DMSO.

Carbohydrate Sequence↗
PubMed1998

A chitin-binding domain in a marine bacterial chitinase and other microbial chitinases: implications for the ecology and evolution of 1,4-beta-glycanases.

To examine the ecology and evolution of microbial chitinases, especially the chitin-binding domain, one of the chitinase genes (chiA) from the marine bacterium Vibrio harveyi was analysed. The deduced amino acid sequence of ChiA is not very similar overall to other proteins, except for two regions, the putative catalytic and chitin-binding domains. Among all bacterial chitinases sequenced to date, there is no relationship between percentage similarity of catalytic domains and chitin-binding domains in pairwise comparisons, suggesting that these two domains have evolved separately. The chitin-binding domain appears to be evolutionarily conserved among many bacterial chitinases and is also somewhat similar to cellulose-binding domains found in microbial cellulases and xylanases. To investigate the role of the chitin-binding domain, clones producing versions of ChiA with or without this domain were examined. One version with the domain (ChiA1) bound to and hydrolysed chitin, whereas a truncated ChiA without the putative chitin-binding domain (ChiA2) did not bind to chitin, but it could hydrolyse chitin, although not as well. ChiA1 diffused more slowly in agarose containing colloidal chitin than ChiA2, but diffusion of the two proteins in agarose without colloidal chitin was similar. These results indicate that the chitin-binding domain helps determine the movement of chitinase along N-acetylglucosamine strands and within environments containing chitin.

Amino Acid Sequence↗
PubMed1994

The roles of the C-terminal domain and type III domains of chitinase A1 from Bacillus circulans WL-12 in chitin degradation.

The mature form of chitinase A1 from Bacillus circulans WL-12 comprises a C-terminal domain, two type III modules (domains), and a large N-terminal domain which contains the catalytic site of the enzyme. In order to better define the roles of these chitinase domains in chitin degradation, modified chiA genes encoding various deletions of chitinase A1 were constructed. The modified chiA genes were expressed in Escherichia coli, and the gene products were analyzed after purification by high-performance liquid chromatography. Intact chitinase A1 specifically bound to chitin, while it did not show significant binding activity towards partially acetylated chitosan and other insoluble polysaccharides. Chitinases lacking the C-terminal domain lost much of this binding activity to chitin as well as colloidal chitin-hydrolyzing activity. Deletion of the type III domains, on the other hand, did not affect chitin-binding activity but did result in significantly decreased colloidal chitin-hydrolyzing activity. Hydrolysis of low-molecular-weight substrates, soluble high-molecular-weight substrates, and insoluble high-molecular-weight substrates to which chitinase A1 does not bind were not significantly affected by these deletions. Thus, it was concluded that the C-terminal domain is a chitin-binding domain required for the specific binding to chitin and that this chitin-binding activity is important for efficient hydrolysis of the sufficiently acetylated chitin. Type III modules are not directly involved in the chitin binding but play an important functional role in the hydrolysis of chitin by the enzyme bound to chitin.

Amino Acid Sequence↗
PubMed1996

The chsD and chsE genes of Aspergillus nidulans and their roles in chitin synthesis.

Two chitin synthase genes, chsD and chsE, were identified from the filamentous ascomycete Aspergillus nidulans. In a region that is conserved among chitin synthases, the deduced amino acid sequences of chsD and chsE have greater sequence identity to the polypeptides encoded by the Saccharomyces cerevisiae CHS3 gene (also named CSD2, CAL1, DIT101, and KTI1) and the Candida albicans CHSE gene than to other chitin synthases. chsE is more closely related to the CHS3 genes, and this group constitutes the class IV chitin synthases. chsD differs sufficiently from the other classes of fungal chitin synthase genes to constitute a new class, class V. Each of the wild-type A. nidulans genes was replaced by a copy that had a substantial fraction of its coding region replaced by the A. nidulans argB gene. Hyphae from both chsD and chsE disruptants contain about 60-70% of the chitin content of wild-type hyphae. The morphology and development of chsE disruptants are indistinguishable from those of wild type. Nearly all of the conidia of chsD disruption strains swell excessively and lyse when germinated in low osmotic strength medium. Conidia that do not lyse produce hyphae that initially have normal morphology but subsequently lyse at subapical locations and show ballooned walls along their length. The lysis of germinating conidia and hyphae of chsD disruptants is prevented by the presence of osmotic stabilizers in the medium. Conidiophore vesicles from chsD disruption strains frequently swell excessively and lyse, resulting in colonies that show reduced conidiation. These properties indicate that chitin synthesized by the chsD-encoded isozyme contributes to the rigidity of the walls of germinating conidia, of the subapical region of hyphae, and of conidiophore vesicles, but is not necessary for normal morphology of these cells. The phenotypes of chsD and chsE disruptants indicate that the chitin synthesized by each isozyme serves a distinct function. The propensity of a chsD disruptant for osmotically induced lysis was compared to that of strains carrying two other mutations (tsE6 and orlA::trpC) which also result in reduced chitin content vegetative cell lysis. The concentration of osmotic stabilizer necessary to remedy the lysis of strains carrying the three mutations is inversely related to the chitin content of each strain. This finding directly demonstrates the importance of chitin to the integrity of the cell wall and indicates that agents that inhibit the chsD-encoded chitin synthase could be useful anti-Aspergillus drugs.

Amino Acid Sequence↗
PubMed2005

An interactional network of genes involved in chitin synthesis in Saccharomyces cerevisiae.

BACKGROUND: In S. cerevisiae the beta-1,4-linked N-acetylglucosamine polymer, chitin, is synthesized by a family of 3 specialized but interacting chitin synthases encoded by CHS1, CHS2 and CHS3. Chs2p makes chitin in the primary septum, while Chs3p makes chitin in the lateral cell wall and in the bud neck, and can partially compensate for the lack of Chs2p. Chs3p requires a pathway of Bni4p, Chs4p, Chs5p, Chs6p and Chs7p for its localization and activity. Chs1p is thought to have a septum repair function after cell separation. To further explore interactions in the chitin synthase family and to find processes buffering chitin synthesis, we compiled a genetic interaction network of genes showing synthetic interactions with CHS1, CHS3 and genes involved in Chs3p localization and function and made a phenotypic analysis of their mutants. RESULTS: Using deletion mutants in CHS1, CHS3, CHS4, CHS5, CHS6, CHS7 and BNI4 in a synthetic genetic array analysis we assembled a network of 316 interactions among 163 genes. The interaction network with CHS3, CHS4, CHS5, CHS6, CHS7 or BNI4 forms a dense neighborhood, with many genes functioning in cell wall assembly or polarized secretion. Chitin levels were altered in 54 of the mutants in individually deleted genes, indicating a functional relationship between them and chitin synthesis. 32 of these mutants triggered the chitin stress response, with elevated chitin levels and a dependence on CHS3. A large fraction of the CHS1-interaction set was distinct from that of the CHS3 network, indicating broad roles for Chs1p in buffering both Chs2p function and more global cell wall robustness. CONCLUSION: Based on their interaction patterns and chitin levels we group interacting mutants into functional categories. Genes interacting with CHS3 are involved in the amelioration of cell wall defects and in septum or bud neck chitin synthesis, and we newly assign a number of genes to these functions. Our genetic analysis of genes not interacting with CHS3 indicate expanded roles for Chs4p, Chs5p and Chs6p in secretory protein trafficking and of Bni4p in bud neck organization.

Cell Wall↗
PubMed2001

Preparation and characterization of chitin beads as a wound dressing precursor.

Chitin was dissolved in N, N-dimethylacetamide/5% lithium chloride (DMAc/5%LiCl) to form a 0.5% chitin solution. Chitin beads were formed by dropping the 0.5% chitin solution into a nonsolvent coagulant, ethanol. The beads were left in ethanol for 24 h to permit hardening, consolidation, and removal of residual DMAc/5%LiCl solvent in order to give spherical chitin beads uniform size distribution. The ethanol-gelled chitin beads had an average diameter of 535 microm. The chitin beads were subsequently activated in 50% (w/v) NaOH solution and reacted with 1.9 M monochloroacetic acid/2-propanol solution to introduce a carboxymethylated surface layer to the chitin beads. The bilayer character of the surface-carboxymethylated chitin (SCM-chitin) beads was verified by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and confocal microscopy. The bilayered SCM-chitin beads were found to absorb up to 95 times their dry weight of water. These SCM-chitin beads have potential as a component of wound dressings.

Algorithms↗
PubMed2005

Insect chitin synthases: a review.

Chitin is the most widespread amino polysaccharide in nature. The annual global amount of chitin is believed to be only one order of magnitude less than that of cellulose. It is a linear polymer composed of N-acetylglucosamines that are joined in a reaction catalyzed by the membrane-integral enzyme chitin synthase, a member of the family 2 of glycosyltransferases. The polymerization requires UDP-N-acetylglucosamines as a substrate and divalent cations as co-factors. Chitin formation can be divided into three distinct steps. In the first step, the enzymes' catalytic domain facing the cytoplasmic site forms the polymer. The second step involves the translocation of the nascent polymer across the membrane and its release into the extracellular space. The third step completes the process as single polymers spontaneously assemble to form crystalline microfibrils. In subsequent reactions the microfibrils combine with other sugars, proteins, glycoproteins and proteoglycans to form fungal septa and cell walls as well as arthropod cuticles and peritrophic matrices, notably in crustaceans and insects. In spite of the good effort by a hardy few, our present knowledge of the structure, topology and catalytic mechanism of chitin synthases is rather limited. Gaps remain in understanding chitin synthase biosynthesis, enzyme trafficking, regulation of enzyme activity, translocation of chitin chains across cell membranes, fibrillogenesis and the interaction of microfibrils with other components of the extracellular matrix. However, cumulating genomic data on chitin synthase genes and new experimental approaches allow increasingly clearer views of chitin synthase function and its regulation, and consequently chitin biosynthesis. In the present review, I will summarize recent advances in elucidating the structure, regulation and function of insect chitin synthases as they relate to what is known about fungal chitin synthases and other glycosyltransferases.

Amino Acid Sequence↗
PubMed1990

Circular dichroism study of membrane dynamics. Effects of carboxymethyl-chitin.

The circular dichroism (CD) active phospholipid bis(4'-n-octanoxyazobenzene-4-carboxyl)-L-alpha-phosphatidylcholin e (CDPC) was used to study the effects of carboxymethyl-chitin (CM-chitin) on the membrane dynamics. For this purpose, CD and electronic spectra were observed for a mixture of CM-chitin and liposomes composed of CDPC and egg lecithin (EPC) (50% CDPC-EPC-liposomes), and for a mixture of CM-chitin, 50% CDPC-EPC-liposomes, and EPC-liposomes. CM-chitin at concentrations higher than ca. 10(-5) M induced the increase of absorbance at 600 nm synchronized with the dilution of CDPC in 50% CDPC-EPC-liposomes by EPC matrix, indicating that CM-chitin induces the fusion among a few liposomes and/or the lipid transfer through the transient liposome fusion. Temperature dependent CD spectra of a mixture of the 50% CDCP-EPC-liposomes and CM-chitin suggested that even high concentration of CM-chitin has no significant perturbation of the lipid organization in the membranes. The effects of CM-chitin on the leakage of [3H]sucrose from the EPC-liposomes were also studied. By the presence of 5 X 10(-6) M CM-chitin, the half-life for leakage of [3H]sucrose in plasma was increased by 4 times. This effect of CM-chitin was reduced by chitinase, while no effect was observed with lysozyme, suggesting that CM-chitin molecules are adsorbed on the liposome surface and stabilize the liposomes against the plasma proteins.

Animals↗
PubMed2002

Characterization of early, chitin-induced gene expression in Arabidopsis.

Three genes (i.e., a zinc finger protein, a lectin-like protein, and AtMPK3), previously shown to respond to chitin elicitation in microarray experiments, were used to examine the response of Arabidopsis spp. to chitin addition. Maximum induction for all three genes was found upon addition of crab-shell chitin at 100 mg per liter. Threefold induction was found with a chitin concentration as low as 10(-4) mg per liter. The specificity of this response was examined using purified chitin oligomers (degree of polymerization = 2 to 8). The larger chitin oligomers (hexamer to octamer), were most effective in inducing expression of the three genes assayed. Gene induction was observed after the addition of 1 nM chitin octamer. The protein kinase inhibitors staurosporine and K252a effectively suppressed chitin-induced gene expression, while the protein phosphatase inhibitors calyculin A and okadaic acid induced the accumulation of mRNA in the absence of chitin. The phosphorylation event necessary for transmission of the chitin signal was completed within the first 20 min of chitin addition. The level of chitin-induced gene expression of the lectin-like protein and AtMPK3 was not significantly changed in mutants blocked in the jasmonic acid (JA, jar1)-, ethylene (ein2)-, or salicylic acid (SA, pad4, npr1, and eds5)-dependent pathway. In contrast, expression of mRNA for the zinc finger protein was reduced in the mutants affected in the JA- or SA-dependent pathway.

Arabidopsis↗
PubMed1989

Inhibitory effect of chitin heparinoids on the lung metastasis of B16-BL6 melanoma.

Structure-function studies for the antimetastatic activity of chemically modified chitin heparinoids composed of N-acetyl glucosamine units were performed in an experimental lung metastasis model. 6-O-Sulfated chitin (S-chitin) significantly inhibited the lung tumor colonization in proportion to the degree of sulfation. However, 6-O- and N-sulfated but partially N-deacetylated chitin (S-chitosan), and 6-O-carboxymethylated chitin (CM-chitin) had no effect. 6-O-Sulfated CM-chitin (SCM-chitin), which exhibited fairly low levels of anticoagulant activity, was also more effective than intact heparin. Furthermore, SCM-chitin with a high degree of sulfation (SCM-chitin III) caused a marked decrease of the number of lung tumor colonies in the spontaneous lung metastasis model. These results strongly suggest that 6-O-sulfate and N-acetyl groups in the glucosamine unit were required for the anti-metastatic effect of chitin heparinoids as well as heparin, and SCM-chitin III may be of therapeutic benefit for the prevention of tumor metastasis.

Animals↗
PubMed1993

Genetics and molecular biology of chitin synthesis in fungi.

In Saccharomyces cerevisiae, three chitin synthases have been detected. Chitin synthases I and II, the products of the CHS1 and CHS2 genes, respectively, are closely related proteins that require partial proteolysis for activity in vitro. In contrast, chitin synthase III is active in vitro without protease treatment, and three genes, CSD2 (= CAL1), CSD4 (= CAL2), and CAL3, are required for its activity. In the cell, the three enzymes have different functions. Chitin synthase I and II make only a small portion, < 10%, of the cellular chitin. In acidic media, chitin synthase I is required for normal budding. Chitin synthase II is required for normal morphology, septation, and cell separation. Chitin synthase III is required for the synthesis of 90% of the cellular chitin, including the chitin in the bud scars and lateral wall. Mutants defective in chitin synthase III are resistant to Calcofluor and Kluyveromyces lactis killer toxin, they lack alkali-insoluble glucan, and under certain circumstances, they are temperature-sensitive for growth. The available data suggest that many fungi have more than one chitin synthase and that these synthases are related to the S. cerevisiae CHS and CSD gene products.

Amino Acid Sequence↗