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1.
《Bioscience, biotechnology, and biochemistry》2013,77(10):1598-1603
Chitin deacetylase, active in the presence of acetate (96% of the enzymatic activity was retained in the presence of 100 mm sodium acetate), was purified to electrophoretic homogeneity from a culture filtrate of Colletotrichum lindemuthianum (944-fold with a recovery of 4.05%). The enzyme was induced in the medium after the eighth day of incubation simultaneously with the blackening of the medium. The molecular mass of the enzyme was 31.5 kDa and 33 kDa as judged by SDS–PAGE and gel filtration, respectively, suggesting that the enzyme is a single polypeptide. The optimum temperature was 60°C and the optimum pH was 11.5–12.0 when glycol chitin was used as substrate. The enzyme was active toward glycol chitin, partially N-deacetylated water soluble chitin, and chitin oligomers the degrees of polymerization of which were more than four, but was less active with chitin trimer and dimer, and inactive with N-acetylglucosamine. The Km and kcat for glycol chitin were 2.55 mm and 27.1s?1, respectively, and those for chitin pentamer were 414 μm and 83.2s?1, respectively. The reaction rates of the enzyme toward glycol chitin and chitin oligomers seemed to follow the Michaelis–Menten kinetics. 相似文献
2.
Kensuke Naka Rie Yamashita Tohru Nakamura Akira Ohki Shigeru Maeda Keigo Aoi Akinori Takasu Masahiko Okada 《International journal of biological macromolecules》1998,23(4):259-262
Catalase from bovine liver was lyophilized from an aqueous solution containing chitin-graft-poly(2-methyl-2-oxazoline) (3), which was synthesized by the reaction of 52% deacetylated chitin (1) with living poly(2-methyl-2-oxazoline) (2). The rate of consumption of H2O2 in chloroform catalyzed by the lyophilized catalase with 3 was enhanced more than 10 times that by catalase without 3. The dispersibility and solubility of lyophilized catalase with 3 in chloroform were improved in comparison with catalase itself. 相似文献
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4.
Thirteen strains were isolated from different habitats, belonging to two genera, namely Conidiobolus and Basidiobolus, related to saprophytic Entomophthorales. Chitin flake colonization and agar-well diffusion tests were used to screen potential
extracellular chitinase-producing strains in plate assays. Preliminary screening resulted in five chitinase producers that
were further studied quantitatively. Results indicated that studied isolates of this group produced chitinase at different
levels in chitin-containing as well as non-chitin-containing medium. Conidiobolus
coronatus was found to be the most significant chitinase producer, giving 0.261 U/ml using colloidal chitin as a carbon source, among
the isolates under study. This communication also reports the chitinolytic activity of Basidiobolus
haptoporus, the effect of environmental and nutritional parameters on chitinase production, and utilization of fungal biomass as a carbon
source, which hitherto had not been elaborated from this genus. 相似文献
5.
Junji Terao Tadaaki Inoue Shinsuke Yamagata Hiroshi Murakami Setsuro Matsushita 《Bioscience, biotechnology, and biochemistry》2013,77(7):1735-1743
Emulsions of methyl linoleate monohydroperoxides (18:2-monoHP) and methyl linolenate monohydroperoxides (18: 3-monoHP) were incubated with ferrous sulfate and ascorbic acid. Gas chromatography mass spectrometric analysis of the trimethylsilyl and te^butyldimethylsilyl derivatives of the reaction products showed that isomerization and secondary oxidation happen competitively during decomposition of 18:2-monoHP, while the secondary oxidation reaction proceeds preferentially and little isomerization is observed in 18: 3-monoHP. It is suggested that 18:3-monoHP is more susceptible to secondary oxidation than 18:2-monoHP because of 18:3 specific secondary oxidation resulting in hydroperoxy-cyclic peroxides and dihydroperoxides. Moreover, an experiment using 1802 has demonstrated that molecular oxygen is scrambled by isomerization and secondary oxidation. It was confirmed that molecular oxygen is attached preferentially to the C-13 position in the 9-monoHP isomer and C-9 position in the 13-monoHP isomer during degradation of 18:2-monoHP. 相似文献
6.
Fabrication and properties of a porous chitin/chitosan conduit for nerve regeneration 总被引:4,自引:0,他引:4
A porous, biodegradable, natural chitin/chitosan nerve conduit was constructed. Scanning electron microscopy confirmed that it was homogeneous and highly porous. FT-IR spectra showed that there were no residues arising from the preparation process in the conduit. Addition of chitin to the chitosan solution increased the mechanical strength and maximum tensile strength from 7.2 to 9.6 MPa. Preliminary animal tests indicated that porous chitin/chitosan conduits did not swell in vivo and were compatible with surrounding tissue. 相似文献
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8.
甲壳质脱乙酰基酶的研究概况及进展 总被引:1,自引:0,他引:1
甲壳质脱乙酰基酶(chitindeacetylase)最初是从真菌毛霉(Mucor.rouxi)分离纯化的一种乙酰基转移酶。这种酶可以催化脱去甲壳质分子中N-乙酰葡糖胺链上的乙酰基,而使之变成壳多糖[1]。除几种真菌外,在昆虫中也发现了这种酶的存在[2]。真菌的甲壳质脱乙酰基酶主要参与真菌细胞壁的形成[3],还与真菌自溶的过程中的细胞壁裂解有关[4]。最近又发现它参与植物和病原微生物的相互作... 相似文献
9.
Norio Nishi Shin-ichiro Nishimura Akira Ebina Akihiro Tsutsumi Seiichi Tokura 《International journal of biological macromolecules》1984,6(1):53-54
New water-soluble chitin derivatives, chitin phosphate of various degrees of substitution, were successfully prepared by the reaction of chitin with phosphorus pentoxide in methanesulphonic acid. These materials behaved hydrodynamically as typical polyelectrolyte, and showed high ability to adsorb metal ions. 相似文献
10.
本文介绍了甲壳素在生物合成和分解代谢过程中所涉及的相关酶,如甲壳素合成酶、甲壳素水解酶和其它相关酶,讨论了它们在分离纯化、结构鉴定、作用机制与模型、酶的固定化、基因工程以及应用等方面的研究现状和进展,对甲壳素的研究开发以及相关领域具有理论和实际意义 。 相似文献
11.
Chitin synthesis in third-instar Lucilia cuprina larvae cultured at 23 °C was investigated using in vivo and in vitro systems, the latter with whole and with homogenized integuments. Synthesis was at a maximum between 24 and 48h after ecdysis from the second instar. Chitin was deposited in layers, and labeled GlcNAc was rapidly cleared from the hemolymph. In in vitro homogenate systems, the rapid conversion of UDP-([14C]GlcN)Ac to ([14C]GlcN)Ac and its 1-phosphate derivative contributed to the low incorporation of this precursor into chitin. The extent of the conversion was reduced by the addition of KCN or phenylthiourea. In in vivo and in vitro tissue systems the level of incorporation of ([14C]ClcN)Ac was higher than that of UDP-([14C]GlcN)Ac. However, in in vitro homogenate systems there was no difference unless UTP was added when the level of incorporation of only ([14C]GlcN)Ac was increased (by a factor of 9). Incorporation of UDP-([14C]GlcN)Ac, but not that of ([14C]GlcN)Ac, was decreased when larvae were deprived of food. Soluble oligosaccharides were detected in in vitro homogenate systems. They were formed during chitin synthesis and may represent newly initiated chitin chains. A reappraisal of current ideas on chitin synthesis in insects is needed. 相似文献
12.
The chitinase gene chi1 of Aeromonas caviae CB101 encodes an 865-amino-acid protein (with signal peptide) composed of four domains named from the N-terminal as an all-beta-sheet domain ChiN, a triosephosphate isomerase (TIM) catalytic domain, a function-unknown A region, and a putative chitin-binding domain (ChBD) composed of two repeated sequences. The N-terminal 563-amino-acid segment of Chi1 (Chi1DeltaADeltaChBD) shares 74% identity with ChiA of Serratia marcescens. By the homology modeling method, the three-dimensional (3D) structure of Chi1DeltaADeltaChBD was constructed. It fit the structure of ChiA very well. To understand fully the function of the C-terminal module of Chi1 (from 564 to 865 amino acids), two different C-terminal truncates, Chi1DeltaChBD and Chi1DeltaADeltaChBD, were constructed, based on polymerase chain reaction (PCR). Comparison studies of the substrate binding, hydrolysis capacity, and specificity among Chi1 and its two truncates showed that the C-terminal putative ChBD contributed to the insoluble substrate-protein binding and hydrolysis; the A region did not have any function in the insoluble substrate-protein binding, but it did have a role in the chitin hydrolysis: Deletion of the A region caused the enzyme to lose 30-40% of its activity toward amorphous colloidal chitin and soluble chitin, and around 50% toward p-nitrophenyl (pNP)-chitobiose pNP-chitotriose, and its activity toward low-molecular-weight chitooligomers (GlcNAc)3-6 also dropped, as shown by analysis of its digestion processes. This is the first clear demonstration that a domain or segment without a function in insoluble substrate-chitinase binding has a role in the digestion of a broad range of chitin substrates, including low-molecular-weight chitin oligomers. The reaction mode of Chi1 is also described and discussed. 相似文献
13.
海洋生物材料的研究与应用开发刘万顺,陈西广(青岛海洋大学海洋生命学院266003)海洋生物材料是指由生物体产生,具有支持细胞结构和机体形态的一类功能性生物大分子。 相似文献
14.
几丁质不仅是昆虫的表皮和围食膜的主要成分,也是一个非常关键的害虫控制靶标,主要通过几丁质合成酶(chitin synthase,CHS)基因合成。本文在克隆甜菜夜蛾Spodoptera exigua的两个几丁质合成酶基因(SeCHSA和SeCHSB)cDNA和基因组序列的基础上,从基因的5′末端设计特异性引物和构建特定的基因组文库, 采用PCR的方法获得了5′端侧翼序列。通过5′RACE的方法确定SeCHSA和SeCHSB基因的转录起始位点后,获到了启动子序列。这为研究昆虫几丁质合成和转录调控奠定了基础。 相似文献
15.
Sei-ichi Aiba Norihiko Minoura Yukihiko Fujiwara 《International journal of biological macromolecules》1985,7(2):120-121
Novel graft copolymers have been synthesized by the reaction of N-carboxyanhydrides of amino acids with partially deacetylated chitins. The graft copolymers had different swelling ability from the original chitin. 相似文献
16.
D.A. Wharton 《International journal for parasitology》1979,9(2):127-131
Wharton D. A. 1979. The structure of the egg-shell of Porrocaecum enslcaudatum (Nematoda: Ascaridida). International Journal for Parasltology9: 127–131. The egg-shell of Porrocaecum ensicaudatum is oval with an opercular plug at either end. The shell consists of three layers: an inner lipid layer, a middle chitinous layer and an outer vitelline layer. The vitelline layer has strands of particulate material attached to its outer surface. The chitinous layer consists of 8.5 nrn fibrils which are made up of a chitin microfibril core surrounded by a protein coat. The fibrils are oriented randomly or in parallel, there being no indication of helicoidal architecture.The chitinous layer varies in thickness to form a pattern of interconnecting ridges on the surface of the egg. This pattern presumably increases the shell's structural strength. 相似文献
17.
Physiology of microbial degradation of chitin and chitosan 总被引:22,自引:0,他引:22
Graham W. Gooday 《Biodegradation》1990,1(2-3):177-190
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. 相似文献
18.
A commercial chitin, regenerated chitin prepared from chitin solutions in 6.8% NaOH and N-acetylated chitosans with degrees of N-acetylation (DNAc) of 77–93% were subjected to oxidization in water with NaClO and catalytic amounts of 2,2,6,6-tetramethylpiperidinyloxy radical (TEMPO) and NaBr. When regenerated chitin with DNAc of 87% and N-acetylated chitosan with DNAc of 93% were used as starting materials, water-soluble β-1,4-linked poly-N-acetylglucosaminuronic acid (chitouronic acid) Na salts with degrees of polymerization of ca. 300 were obtained quantitatively within 70 min. On the other hand, the original chitin and N-acetylated chitosan with DNAc of 77% did not give water-soluble products, owing to incomplete oxidation. The high crystallinity of the original chitin brought about low reactivity, and the high C2-amino group content of the N-acetylated chitosan with DNAc of 77% led to degradations rather than the selective oxidation at the C6 hydroxyls. The obtained chitouronic acid had low viscosities in water, and clear biodegradability by soil microorganisms. 相似文献
19.
M.E. Jacobs 《Journal of insect physiology》1985,31(6):509-515
Injection of 20 nl of 1.0 M beta-alanine, about the minimal amount needed to produce wild-type tanned phenomenocopies from newly eclosed mutant black Drosophila melanogaster, increases stiffness and puncture-resistance of the wing cuticle. Increasing the concentration of beta-alanine to 2.0 M increases puncture-resistance further. Injection of 1.0 M of the beta-alanine analogue beta-aminoisobutyric acid, does not induce tanning or puncture-resistance, nor does injection of 1.0 M dopamine. However, injection of 1.0 M beta-alanine and 1.0 M dopamine increases puncture-resistance more than an injection of 1.0 M beta-alanine, though not more than an injection of 2.0 M beta-alanine alone. Within 10 min after injection of [3-3H]beta-alanine into newly eclosed normal flies, 3H becomes 8.7 times more concentrated in the cuticle than in an equal area of underlying epidermis. 3H is excluded from the epidermis or cuticle of ebony strains. Ebony strains show a deficiency of cuticular electron-absorbing material, and the cuticular lamellae show a tendency to separate from each other. Compaction of the chitinous lamellae is induced in alkali-detanned pupal sheaths by exposure to nascent quinones of N-acetyldopamine or N-beta-alanyldopamine. Glucosamine, but not N-acetylglucosamine, reacts with such quinones in tanning reactions. Under an infrared beam, black cuticular pigmentation induces more rapid heating of haemocoel fluids than does tan pigmentation. A theory of pigmentation and sclerotization relative to environmental adaptation is presented. 相似文献
20.
甲壳素与虾青素在自然界蕴含丰富,在农业、医药、轻工业、环保等领域有着良好的应用前景.从其性质、生理功能及特性、资源利用等方面作一介绍. 相似文献