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Laila Manni Olfa Ghorbel-Bellaaj Kemel Jellouli Islem Younes Moncef Nasri 《Applied biochemistry and biotechnology》2010,162(2):345-357
Chitin is a polysaccharide found in abundance in the shell of crustaceans. In this study, the protease from Bacillus cereus SV1 was applied for chitin extraction from shrimp waste material of Metapenaeus monoceros. A high level of deproteinization 88.8% ± 0.4 was recorded with an E/S ratio of 20. The demineralization was completely achieved
within 6 h at room temperature in HCl 1.25 M, and the residual content of calcium in chitin was below 0.01%. 13C CP/MAS-NMR spectral analysis of chitin prepared by the enzymatic deproteinization of shrimp wastes was found to be similar
to that obtained by alkaline treatment and to the commercial α-chitin. The degree of N-acetylation, calculated from the spectrum,
was 89.5%. Chitin obtained by treatment with crude protease from B. cereus was converted to chitosan by N-deacetylation, and the antibacterial activity of chitosan solution against different bacteria
was investigated. Results showed that chitosan solution at 50 mg/mL markedly inhibited the growth of most Gram-negative and
Gram-positive bacteria tested. Furthermore, the antioxidant potential of the protein hydrolysates obtained during enzymatic
isolation of chitin was evaluated using various in vitro assays. All the samples exerted remarkable antioxidant activities. These results suggest that enzymatic deproteinization
of the shrimp shell wastes, using B. cereus SV1 protease, could be applicable to the chitin production process. 相似文献
3.
Kemel Arafet Florenci V. González Vicent Moliner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(9):2002-2012
In this work a computational study of the mechanism of inhibition of cruzain, rhodesain, and cathepsin L cysteine proteases by the dipeptidyl nitroalkene Cbz-Phe-Ala-CH=CH-NO2 has been carried out by means of molecular dynamics simulations with hybrid QM/MM potentials. The free-energy surfaces confirmed that the inhibition takes place by the formation of a covalent bond between the protein and the β-carbon atom of the inhibitor. According to the results, the tested inhibitor should be a much more efficient inhibitor of cruzain than of rhodesain, and little activity would be expected against cathepsin L, in total correspondence with the available experimental data. The origin of these differences may lie in the different stabilizing electrostatic interactions established between the inhibitor and the residues of the active site and S2 pocket of these enzymes. These results may be useful for the rational design of new dipeptidyl nitroalkenes with higher and more selective inhibitory activity against cysteine proteases. 相似文献
4.
Ghorbel-Bellaaj O Jellouli K Younes I Manni L Ouled Salem M Nasri M 《Applied biochemistry and biotechnology》2011,164(4):410-425
A solvent-stable protease-producing bacterium was isolated and identified as Pseudomonas aeruginosa A2. The strain was found to produce high level of protease activity when grown in media containing only fresh shrimp waste
(FSW) or shrimp waste powder (SWP), indicating that it can obtain its carbon, nitrogen, and salts requirements directly from
shrimp waste. Maximum protease activities 17,000 and 12,000 U/mL were obtained with 80 g/L SWP and 135 g/L FSW, respectively.
The optimum temperature and pH for protease activity were 60 °C and 8.0, respectively. The crude protease, at different enzyme/substrate
(E/S) ratio, was tested for the deproteinization of shrimp waste to produce chitin. The crude enzyme of P. aeruginosa A2 was found to be effective in the deproteinization of shrimp waste. The protein removals after 3 h hydrolysis at 40 °C
with an E/S ratio of 0.5 and 5 U/mg protein were about 56% and 85%, respectively. 13C CP/MAS-NMR spectral analysis of the chitin prepared by treatment with the crude protease was carried out and was found to
be similar to that of the commercial α-chitin. These results suggest that enzymatic deproteinization of shrimp waste by A2
protease could be applicable to the chitin production process. 相似文献
5.
Bakhtiyarova E. A. Kemel’bekov B. Zh. Bekmagambetova Zh. M. Lipskaya M. A. Chigambaev T. O. Orazymbetova A. K. Ospanova N. A. Mekebaeva A. K. Khan V. A. Mamilov B. E. 《Russian Physics Journal》2017,60(1):190-195
Russian Physics Journal - Quality of oral speech reproduction using stochastic digital systems of information transfer at its statistical compaction is analyzed (on the example of Russian and... 相似文献
6.
Dr. Kemel Arafet Prof. Florenci V. González Prof. Vicent Moliner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(39):10142-10150
A computational study of the two possible inhibition mechanisms of rhodesain cysteine protease by the dipeptidyl enoate Cbz-Phe-Leu-CH=CH−CO2C2H5 has been carried out by means of molecular dynamics simulations with hybrid QM/MM potentials. The low free energy barriers confirm that the Cys25 residue can attack both Cβ and C1 atoms of the inhibitor, confirming a dual mode of action in the inhibition of the rhodesain by enoates. According to the results, the inhibition process through the Cys25 attack on the Cβ atom of the inhibitor is an exergonic and irreversible process, while the inhibition process when Cys25 attacks on the C1 atom of the inhibitor is and exergonic but reversible process. The interactions between the inhibitor and rhodesain suggest that P2 is the most important fragment to consider in the design of new efficient inhibitors of rhodesain. These results may be useful for the design of new inhibitors of rhodesain and other related cysteine proteases based on dipeptidyl enoates scaffolds. 相似文献
7.
Laila Manni Kemel Jellouli Olfa Ghorbel-Bellaaj Rym Agrebi Anissa Haddar Alya Sellami-Kamoun Moncef Nasri 《Applied biochemistry and biotechnology》2010,160(8):2308-2321
The current increase in amount of shrimp wastes produced by the shrimp industry has led to the need in finding new methods
for shrimp wastes disposal. In this study, an extracellular organic solvent- and oxidant-stable metalloprotease was produced
by Bacillus cereus SV1. Maximum protease activity (5,900 U/mL) was obtained when the strain was grown in medium containing 40 g/L shrimp wastes
powder as a sole carbon source. The optimum pH, optimum temperature, pH stability, and thermal stability of the crude enzyme
preparation were pH 8.0, 60 °C, pH 6–9.5, and <55 °C, respectively. The crude protease was extremely stable toward several
organic solvents. No loss of activity was observed even after 60 days of incubation at 30 °C in the presence of 50% (v/v) dimethyl sulfoxide and ethyl ether; the enzyme retained more than 70% of its original activity in the presence of ethanol
and N,N-dimethylformamide. The protease showed high stability toward anionic (SDS) and non-ionic (Tween 80, Tween 20, and Triton
X-100) surfactants. Interestingly, the activity of the enzyme was significantly enhanced by oxidizing agents. In addition,
the enzyme showed excellent compatibility with some commercial liquid detergents. The protease of B. cereus SV1, produced under the optimal culture conditions, was tested for shrimp waste deproteinization in the preparation of chitin.
The protein removal with a ratio E/S of 20 was about 88%. The novelties of the SV1 protease include its high stability to organic solvents and surfactants. These
unique properties make it an ideal choice for application in detergent formulations and enzymatic peptide synthesis. In addition,
the enzyme may find potential applications in the deproteinization of shrimp wastes to produce chitin. 相似文献
8.
Abdullin Kh. A. Kemel’bekova A. E. Lisitsyn V. M. Mukhamedshina D. M. Nemkaeva R. R. Tulegenova A. T. 《Physics of the Solid State》2019,61(10):1840-1845
Physics of the Solid State - A simple method of pyrolysis of an aerosol solution of yttrium, aluminum, and cerium nitrates with the addition of urea or citric acid, followed by brief annealing, is... 相似文献
9.
Ospanova N. A. Kemel’bekov B. Zh. Bakhtiyarova E. A. Zhetpisbaeva A. T. Kulakaeva A. E. Kosyakov I. O. 《Russian Physics Journal》2015,58(3):289-292
Russian Physics Journal - Results of experimental studies of the extinction coefficient of optical fibers preliminary irradiated by thermal neutrons and compressed are presented. In this case,... 相似文献
10.
Kemel Arafet Natalia Serrano-Aparicio Alessio Lodola Adrian J. Mulholland Florenci V. Gonzlez Katarzyna
widerek Vicent Moliner 《Chemical science》2021,12(4):1433
The SARS-CoV-2 main protease (Mpro) is essential for replication of the virus responsible for the COVID-19 pandemic, and one of the main targets for drug design. Here, we simulate the inhibition process of SARS-CoV-2 Mpro with a known Michael acceptor (peptidyl) inhibitor, N3. The free energy landscape for the mechanism of the formation of the covalent enzyme-inhibitor product is computed with QM/MM molecular dynamics methods. The simulations show a two-step mechanism, and give structures and calculated barriers in good agreement with experiment. Using these results and information from our previous investigation on the proteolysis reaction of SARS-CoV-2 Mpro, we design two new, synthetically accessible N3-analogues as potential inhibitors, in which the recognition and warhead motifs are modified. QM/MM modelling of the mechanism of inhibition of Mpro by these novel compounds indicates that both may be promising candidates as drug leads against COVID-19, one as an irreversible inhibitor and one as a potential reversible inhibitor.QM/MM simulations identify the mechanism of reaction of N3, a covalent peptidyl inhibitor of SARS-CoV-2 main protease. Modelling of two novel proposed compounds, B1 and B2, suggests that reversibility of covalent inhibition could be tailored. 相似文献