Alkaline N-deacetylation of chitin enhanced by flash treatments. Reaction kinetics and structure modifications

Focher, B.; Beltrame, P.; Naggi, Anna Maria; Torri, Giangiacomo

doi:10.1016/0144-8617(90)90090-f

Cited by 264 publications

(157 citation statements)

References 15 publications

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“…An increase in the intensity of this peak in chito-oligomeric-monomeric mixture compared with native chitosan further confirmed increase in DA, and from these it is evident that both papain and Pronase result in the release of GlcNAc/GlcNAc-rich oligomers. A slight shift in the peak around 3370 cm −1 was indicative of orderliness of the products, probably due to increase in DA [24]. The region between 1420 and 1435 cm −1 is considered to be conformation-sensitive for polysaccharides, which depends on the orientation of the primary hydroxy group, and its shift in the chito-oligomeric-monomeric mixture Figure 4 CD spectra of () native chitosan, and chito-oligomericmonomeric mixture obtained using papain (᭹) and ( ) Pronase compared with native chitosan indicates a change in the secondary structural environment [25].…”

Section: Ftirmentioning

confidence: 99%

Characterization of chito-oligosaccharides prepared by chitosanolysis with the aid of papain and Pronase, and their bactericidal action against Bacillus cereus and Escherichia coli

Kumar

Varadaraj

Gowda

et al. 2005

Biochemical Journal

201

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Papain (from papaya latex; EC 3.4.22.2) and Pronase (from Streptomyces griseus; EC 3.4.24.31) caused optimum depolymerization of chitosan at pH 3.5 and 37• C, resulting in LMMC (low molecular mass chitosan) and chito-oligomeric-monomeric mixture. The yield of the latter was 14-16 % and 14-19 % respectively for papain-and Pronase-catalysed reactions, depending on the reaction time (1-5 h). HPLC revealed the presence of monomer(s) and oligomers of DP (degree of polymerization) 2-6, which was also confirmed by matrix-assisted laser-desorption ionization-time-of-flight MS. Along with the chito-oligomers, the appearance of only GlcNAc (N-acetylglucosamine) in Pronasecatalysed chitosanolysis was indicative of its different action pattern compared with papain. Fourier-transform infrared, liquidstate 13 C-NMR spectra and CD analyses of chito-oligomericmonomeric mixture indicated the release of GlcNAc/GlcNAc-rich oligomers. The monomeric sequence at the non-reducing ends of chito-oligomers was elucidated using N-acetylglucosaminidase. The chito-oligomeric-monomeric mixture showed better growth inhibitory activity towards Bacillus cereus and Escherichia coli compared with native chitosan. Optimum growth inhibition was observed with chito-oligomers of higher DP having low degree of acetylation. The latter caused pore formation and permeabilization of the cell wall of B. cereus, whereas blockage of nutrient flow due to the aggregation of chito-oligomers-monomers was responsible for the growth inhibition and lysis of E. coli, which were evidenced by scanning electron microscopy analysis. The spillage of cytoplasmic enzymes and native PAGE of the cellfree supernatant of B. cereus treated with chito-oligomeric-monomeric mixture further confirmed bactericidal activity of the latter. Use of papain and Pronase, which are inexpensive and easily available, for chitosanolysis, is of commercial importance, as the products released are of considerable biomedical value.

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Section: Ftirmentioning

confidence: 99%

Characterization of chito-oligosaccharides prepared by chitosanolysis with the aid of papain and Pronase, and their bactericidal action against Bacillus cereus and Escherichia coli

Kumar

Varadaraj

Gowda

et al. 2005

Biochemical Journal

201

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“…Para cálculo do grau de cristalinidade das quitinas e quitosanas foi utilizada a relação 1. 15,18 I CR (%) = {[I(θc)-I(θa)]/ I(θc)} x 100…”

Section: Difração De Raios-xunclassified

“…As deformações axiais C-N das amidas e aminas são observadas em 1420 e 1350-1000 cm -1 , respectivamente. 18,19 A principal diferença entre os espectros das quitinas e das quitosanas (Figura 4b) pode ser observada na região em que ocorrem as bandas de amida I, que são menos intensas e menos resolvidas no caso de quitosanas. Além disso, entre 3000-2800 cm -1 os espectros no infravermelho das amostras de quitina apresentam cinco bandas de estiramento CH, sendo três bem distintas, enquanto que nos espectros das quitosanas são observadas apenas duas bandas.…”

Section: Esquema 2 Preparação Das Soluções De Quitosanas Empregadasunclassified

Obtenção e caracterização de α-quitina e quitosanas de cascas de Macrobrachium rosembergii

Battisti¹,

Filho²

2008

Quím. Nova

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“…The chitosan sample was prepared from chitin [22] and the degree of deacetylation was determined by titration [1] to be 76%. Chitin powder was prepared from dry shrimp shell by removing protein, inorganic materials and pigments according to the procedures described in ref.…”

Section: Methodsmentioning

confidence: 99%

Modified chitosan, 7 Graft copolymerization of methacrylonitrile onto chitosan using ammonium persulfate initiator

2004

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Graft copolymerization of methacrylonitrile (MAN) onto chitosan using ammonium persulfate (APS) as an initiator was studied. The reactions were carried out under argon atmosphere in a homogenous aqueous phase containing a small portion of acetic acid (AcOH). Evidence of graft copolymerization was obtained by FTIR spectroscopy, e.g., the appearance of nitrile in the spectrum of chitosan-graftpolymethacrylonitrile. The synthetic conditions were systematically optimized through studying the influential factors including temperature, as well as concentrations of initiator, MAN, AcOH, sodium dodecyl sulfate surfactant (SDS) and chitosan. The effects of individual factors were investigated by calculating and monitoring the variation of the grafting parameters, i.e., grafting ratio, grafting efficiency, add-on value, homopolymer content, and total conversion. The optimum condition was achieved at APS 0.0108 mol/L, MAN 0.201 mol/L, 80°C, SDS 0.0016 mol/L, chitosan 0.5 g, AcOH 0.0086 mol/L. The overall activation energy for the graft copolymerization was determined to be 7.3 kJ/mol.

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Alkaline N-deacetylation of chitin enhanced by flash treatments. Reaction kinetics and structure modifications

Cited by 264 publications

References 15 publications

Characterization of chito-oligosaccharides prepared by chitosanolysis with the aid of papain and Pronase, and their bactericidal action against Bacillus cereus and Escherichia coli

Characterization of chito-oligosaccharides prepared by chitosanolysis with the aid of papain and Pronase, and their bactericidal action against Bacillus cereus and Escherichia coli

Obtenção e caracterização de α-quitina e quitosanas de cascas de Macrobrachium rosembergii

Modified chitosan, 7 Graft copolymerization of methacrylonitrile onto chitosan using ammonium persulfate initiator

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