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1.
J. appl. oral sci ; 27: e20180453, 2019. graf
Article in English | LILACS, BBO | ID: biblio-1012522

ABSTRACT

Abstract Objective This study was designed for the chemical activation of a 35% hydrogen peroxide (H2O2) bleaching gel to increase its whitening effectiveness and reduce its toxicity. Methodology First, the bleaching gel - associated or not with ferrous sulfate (FS), manganese chloride (MC), peroxidase (PR), or catalase (CT) - was applied (3x 15 min) to enamel/dentin discs adapted to artificial pulp chambers. Then, odontoblast-like MDPC-23 cells were exposed for 1 h to the extracts (culture medium + components released from the product), for the assessment of viability (MTT assay) and oxidative stress (H2DCFDA). Residual H2O2 and bleaching effectiveness (DE) were also evaluated. Data were analyzed with one-way ANOVA complemented with Tukey's test (n=8. p<0.05). Results All chemically activated groups minimized MDPC-23 oxidative stress generation; however, significantly higher cell viability was detected for MC, PR, and CT than for plain 35% H2O2 gel. Nevertheless, FS, MC, PR, and CT reduced the amount of residual H2O2 and increased bleaching effectiveness. Conclusion Chemical activation of 35% H2O2 gel with MC, PR, and CT minimized residual H2O2 and pulp cell toxicity; but PR duplicated the whitening potential of the bleaching gel after a single 45-minute session.


Subject(s)
Tooth Bleaching/methods , Tooth Bleaching Agents/toxicity , Tooth Bleaching Agents/chemistry , Hydrogen Peroxide/toxicity , Hydrogen Peroxide/chemistry , Reference Values , Time Factors , Ferrous Compounds/chemistry , Catalase/chemistry , Cell Survival , Cells, Cultured , Chlorides/chemistry , Reproducibility of Results , Analysis of Variance , Manganese Compounds/chemistry , Color , Peroxidase/chemistry , Statistics, Nonparametric , Dental Pulp/chemistry , Dental Pulp/diagnostic imaging , Dentin/drug effects , Dentin/chemistry , Odontoblasts/drug effects
2.
Indian J Biochem Biophys ; 2015 Apr; 52 (2): 189-195
Article in English | IMSEAR | ID: sea-158219

ABSTRACT

The carboxylic groups of glutamic acid and aspartic acid residues of catalase (CAT) were chemically modified using the treatment of the enzyme with 1-ethyl-3-(3'-dimethylamino) carbodiimide hydrochloride (EDC) and neomycin. The effect of covalent attachment of neomycin on the enzymatic activity, conformational and aggregation properties of CAT was investigated. The modification of CAT with different concentrations of neomycin showed two different types of behavior, depending up on the concentration range of neomycin. In the concentration range from 0.0 to 5.2 mM, neomycin-modified CAT, compared to the native enzyme exhibited higher α-helix content, reduced surface hydrophobicity, little enhancement in CAT activity and a better protection against thermal aggregation, whereas at concentrations greater than 5.2 mM, the modified enzyme exhibited a significant decrease in CAT activity and an increase in random coil content which may result in disorder in the protein structure and increase in thermal aggregation. This modification is a rapid and simple approach to investigate the role of aspartate and glutamate residues in the structure, function and folding of CAT.


Subject(s)
Aminoglycosides/chemistry , Catalase/chemistry , Catalase/metabolism , Catalase/physiology , Neomycin/chemistry , Surface Properties/drug effects
3.
Indian J Biochem Biophys ; 2007 Feb; 44(1): 38-43
Article in English | IMSEAR | ID: sea-28315

ABSTRACT

The covalent immobilization of bovine liver catalase (CAT) on to florisil via glutaraldehyde was investigated. Optimum immobilization pH and temperature were determined as pH 6.0, 10 degrees C respectively, while the amount of initial CAT per g of carrier and immobilization time was determined as 5 mg g(-1) and 120 min, respectively. The Vmax values for free and immobilized CAT were found to be 1.7 x 10(5) and 2.0 x 10(4) micromol H2O2 min(-1) mg protein(-1), respectively, whereas KM values were 33.3 mM and 1722.0 mM respectively. Operational stability was determined by using a stirred batch-type column reactor. Immobilized CAT retained about 40% of its initial activity after 50 uses. It showed higher storage stability than free CAT at 4 degrees C and 25 degrees C. Its storage stability increased with increasing relative humidity (RH) from 0 to 20% of the medium. The highest storage stability was obtained in 20% RH, however, further increase in RH from 40 to 100% significantly decreased the storage stability.


Subject(s)
Animals , Buffers , Catalase/chemistry , Cattle , Drug Storage , Enzyme Stability , Enzymes, Immobilized/chemistry , Hydrogen-Ion Concentration , Kinetics , Liver/enzymology , Magnesium Silicates
4.
Indian J Biochem Biophys ; 2006 Aug; 43(4): 211-6
Article in English | IMSEAR | ID: sea-28873

ABSTRACT

High throughput macromolecular structure determination is very essential in structural genomics as the available number of sequence information far exceeds the number of available 3D structures. ACORN, a freely available resource in the CCP4 suite of programs is a comprehensive and efficient program for phasing in the determination of protein structures, when atomic resolution data are available. ACORN with the automatic model-building program ARP/wARP and refinement program REFMAC is a suitable combination for the high throughput structural genomics. ACORN can also be run with secondary structural elements like helices and sheets as inputs with high resolution data. In situations, where ACORN phasing is not sufficient for building the protein model, the fragments (incomplete model/dummy atoms) can again be used as a starting input. Iterative ACORN is proved to work efficiently in the subsequent model building stages in congerin (PDB-ID: lis3) and catalase (PDB-ID: 1gwe) for which models are available.


Subject(s)
Animals , Automation , Catalase/chemistry , Computational Biology/instrumentation , Crystallography, X-Ray , Eels , Galectins/chemistry , Genomics/methods , Micrococcus luteus/metabolism , Models, Chemical , Models, Molecular , Protein Conformation , Proteins/chemistry , Proteomics/methods , Software
5.
Indian J Exp Biol ; 2005 Nov; 43(11): 1058-67
Article in English | IMSEAR | ID: sea-62992

ABSTRACT

Short-term hyperthyroidism, induced by daily administration of T3 (20 microg/100g body weight) for one, three, and five days consecutively, modulates oxidative stress and antioxidant defence parameters in mitochondrial and postmitochondrial fractions of testis in adult rats. Alteration in antioxidant defences along with oxidative stress parameters in testis by thyroid hormone was found to be associated with a decline in the number of sperms and disturbances in histoarchitecture of seminiferous tubules in the testes; the results indicated that induced hyperthyroid state altered testicular physiology by influencing antioxidant defence system of testes.


Subject(s)
Animals , Antioxidants/metabolism , Blotting, Western , Body Weight , Carbon/chemistry , Catalase/chemistry , Disease Models, Animal , Hyperthyroidism/pathology , Lipid Peroxidation , Male , Oxidants/chemistry , Oxidative Stress , Rats , Rats, Wistar , Reactive Oxygen Species , Superoxide Dismutase/metabolism , Testis/metabolism , Thiobarbituric Acid Reactive Substances , Time Factors , Tissue Distribution
6.
Rev. cuba. invest. bioméd ; 15(2): 75-81, jul.-dic. 1996. ilus
Article in Spanish | LILACS | ID: lil-184543

ABSTRACT

Las especies reactivas de oxigeno estan implicadas en el dano celular. Sin embargo, en el organismo existe un sistema de proteccion formulado por compuestos y enzimas antioxidantes que participan en las transformaciones de dichas especies. La catalasa es una de las enzimas involucradas en la destruccion del peroxido de hidrogeno generado durante el metabolismo celular. Sus caracteristicas estructurales, asi como su papel en algunas situaciones fisiopatologicas se tratan en el presente articulo


Subject(s)
Catalase/chemistry , Reactive Oxygen Species , Free Radicals
7.
Indian J Biochem Biophys ; 1992 Dec; 29(6): 465-8
Article in English | IMSEAR | ID: sea-28720

ABSTRACT

Positron annihilation studies have been carried out in two enzymes, lysozyme and catalase. Temperature dependence of the positron lifetimes in these two enzymes has been investigated. The results explained in terms of the free volume model and fluctuations between different conformational microstates of enzyme structures provide a new insight into the mechanism of bio-activity of these enzymes.


Subject(s)
Catalase/chemistry , Kinetics , Muramidase/chemistry , Protein Conformation , Thermodynamics
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