Topic
Chitin
About: Chitin is a research topic. Over the lifetime, 6590 publications have been published within this topic receiving 253993 citations.
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TL;DR: An hypothesis is presented for the function of the complex chitinolytic system of the fungal hypha in branching and, possibly, also in apical growth.
Abstract: SUMMARY: Enzymological evidence has been sought for the purported involvement of chitinolysis in vegetative growth of filamentous fungi. A procedure has been developed for the production of fast growing and morphologically homogeneous exponential phase mycelium of the non-septate dimorphic zygomycete Mucor rouxii. A partially purified extract of this material has been subjected to gel-permeation chromatography and the chitinolytic activity of eluate fractions has been assessed using colloidal and nascent chitin and 3,4-dinitrophenyl tetra-N-acetylchitotetraoside [3,4-DNP-(GlcNAc)4] as substrates. Exponentially growing (td = 1·1 h) mycelium consisting of single short-branched hyphae contains at least seven chitinases. The two particulate ones have not been studied in detail. The soluble chitinases hydrolyse (pseudo)chito-oligomers by random cleavage of internal β-1,4-bonds (and not by processing) and have a minimum chain-length requirement of n = 4. They are clearly distinct from β-N-acetylglucosaminidase (β-GlcNAc'ase) with respect to their chromatographic behaviour, substrate chain-length specificity, inhibition by chitobionolactone oxime (K
1 = 175 μM), and non-inhibition by the specific β-GlcNAc'ase inhibitor N-acetylglucosaminono-1,5-lactone oxime. Their pH optima are similar (6·5-7·0), and all can hydrolyse 3,4-DNP-(GlcNAc)4 as well as nascent chitin. With respect to their charge, response to protease treatment, behaviour upon gel-permeation chromatography and ability to use colloidal chitin as a substrate, the soluble chitinases do, however, represent two distinct groups. Type A chitinases are acidic, display partial latency, show an unusual affinity to dextran gel and act weakly on colloidal chitin. Type B chitinases are basic (or neutral) and non-zymogenic, do not behave anomalously upon gel filtration and can degrade preformed chitin. An hypothesis is presented for the function of the complex chitinolytic system of the fungal hypha in branching and, possibly, also in apical growth.
85 citations
TL;DR: The hypothesis that chitosan-coatings are able to develop a close bony apposition or the osseointegration of dental/craniofacial and orthopedic implants is supported.
Abstract: Procedure:Much research is directed at surface modifications to enhance osseointegration of implants. A new potential coating is the biopolymer, chitosan, the deacetylated derivative of the natural polysaccharide, chitin. Chitosan is biocompatible, degradable, nontoxic, and exhibits osteogenic prope
85 citations
TL;DR: Constitutive chitinases were purified from healthy tomato stem and culture filtrates of a tomato isolate of Verticillium albo-atrum and increased activity in infected tissue was due primarily to increased production of the constitutive endo-enzyme found in healthy tomato stems.
Abstract: Constitutive chitinases were purified from healthy tomato stem and culture filtrates of a tomato isolate of Verticillium albo-atrum Both chitinases hydrolyzed chitin, chitosan and 3,4-dinitrophenyl-tetra- N -acetyl-β- d -chitotetraoside, but the tomato enzyme showed enhanced production of N -acetylglucosamine from chitin in the presence of chitobiase The tomato chitinase, purified to homogeneity, had a molecular weight of 27 000–31000 and functioned as an endo-enzyme The partially purified chitinase from V albo-atrum had a molecular weight of 63 000, appeared to be an exo-enzyme and was unaffected by the addition of chitobiase to the reaction mixture It differed from the tomato enzyme in the hydrolysis of chitobiose and in its inhibition by 2-acetamido-2-deoxy- d -gluconolactone The origin of increased chitinase activity in V albo-atrum -infected tomato stem was investigated by comparing the response of chitinase in extracts from healthy and infected stem to pH and temperature and by examining the patterns of activity in healthy and infected stem extracts after gel isoelectric-focusing The enzymes from healthy and infected stem and from V albo-atrum were also compared during the various purification stages The increased activity in infected tissue was due primarily to increased production of the constitutive endo-enzyme found in healthy tomato stems An additional chitinase similar to the fungal enzyme was also present
84 citations
TL;DR: A unique chitin catabolic pathway in T. kodakaraensis is revealed, in which GlcNAc2 produced from chit in is degraded by the concerted action of Tk-Dac and Tk -GlmA, and a novel mechanism for dimer processing using a combination of deacetylation and cleavage is defined.
84 citations
TL;DR: In this article, the spectral dependence of both the chitosan and chitin refractive indices was obtained for wavelengths between 250 and 750 nm. But the spectral properties of chitins were not considered.
84 citations