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Your search keyword '"Laribi-Habchi H"' showing total 2 results
Start Over Author "Laribi-Habchi H" Topic chitinase
2 results on '"Laribi-Habchi H"'

1. Purification and biochemical characterization of a novel acido-halotolerant and thermostable endochitinase from Melghiribacillus thermohalophilus strain Nari2A(T)

Author

Mohamed, S., Bouacem, K., Mechri, S., Addou, N. A., Laribi-Habchi, H., Fardeau, Marie-Laure, Jaouadi, B., Bouanane-Darenfed, A., and Hacene, H.

Subjects
Hydrolytic pattern, Melghiribacillus thermohalophilus, Chitinase, Chitin, Thin-layer chromatography
Abstract

An extracellular acido-thermostable endochitinase (called ChiA-Mt45) from thermohalophilic Melghiribacillus thermohalophilus strain Nari2A(T) gen. nov. sp. nov., was purified and biochemically characterized. The maximum chitinase activity recorded after 48-h of incubation at 55 degrees C was 9000 U/mL. Pure enzyme was obtained after heat treatment (20 min at 90 degrees C) followed by sequential column chromatographies on fast performance liquid chromatography (FPLC) and high performance liquid chromatography (HPLC). Based on MALDI-TOF/MS analysis, the purified enzyme is a monomer with a molecular mass of 45201.10 Da. The 27 residue NH2-terminal sequence of the enzyme showed high homology with Bacillus GH-18 chitinases family. The optimum pH and temperature values for chitinase activity were pH 3.5 and 90 degrees C, respectively. In addition, the enzyme was halotolerant and can be classified as an extremozyme. The pure enzyme was completely inhibited by p-chloromercuribenzoic acid (p-CMB) and N-ethylmaleimide (NEM). Its K-m and k(cat) values were 0.253 mg colloidal chitin/mL and 47000 s(-1), respectively. Interestingly, its catalytic efficiency was higher than those of chitinases ChiA-Hh59 from Hydrogenophilus hirchii KB-DZ44 and chitodextrinase from Streptomyces griseus, and N-acetyl-beta-glucosaminidase from Trichoderma viride. The studied chitinase exhibited high activity towards colloidal chitin, chitin azure, glycol chitin, while it did not hydrolyse chitibiose and amylose. Additionally, thin-layer chromatography (TLC) analysis from chitin-oligosaccharides showed that ChiA-Mt45 acted as an endosplitting enzyme. Overall, the chitinase ChiA-Mt45 may have great potential for the enzymatic degradation of chitin.

Published
2019

2. Chitin oligomers and monomers production by coupling γ radiation and enzymatic hydrolysis.

Author

Dziril, M., Grib, H., Laribi-Habchi, H., Drouiche, N., Abdi, N., Lounici, H., Pauss, A., and Mameri, N.

Subjects
CHITIN, OLIGOMERS, MONOMERS, ENZYMATIC analysis, HYDROLYSIS
Abstract

The main purpose of this study was the chitin enzymatic hydrolysis enhancement by a pretreatment, consisting of chitin exposure to gamma radiation at several doses, ranging from 15 kGy to 210 kGy. The solid chitin molecular weight reduction achieved by Co-60 gamma rays treatment reached a 90% rate at the t used, with a dose of 210 kGy. The partial depolymerization of chitin was realized by irradiation allowing an enzyme affinity increase toward this substrate. The monomers and oligomers obtained from their radiated chitin production rate were almost 100%. It was also demonstrated that the NAG production by enzymatic hydrolysis of irradiated chitin at 210 Gy follows Michaelis–Menton kinetics. [ABSTRACT FROM AUTHOR]

Published
2015
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