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ABSTRACT: Effluent from textile industries were treated with enzyme from white rot fungi isolated from outskirts of Mumbai and identified as Polyporus rubidus in our laboratory. Decolorisation of 4 Reactive dyes commonly found in the effluents such as Reactive bue, Reactive orange, Ramazol black and Congo red was examined by treatment with enzyme from Polyporus rubidus. Treatment of effluent was done in a laboratory scale bioreactor constructed with laccase immobilized Na-alginate beads. Greater than 80% of dyes were degraded within 5 days under stationary incubation conditions. The enzyme had a maxmimum activity of 17.1U after 3 days and was found to be secreted extracellularly by Polyporus rubidus. In this study the Polyporus rubidus has been reported for the first time to have laccase activity offering a promising possibility to develop an easy and cost effective method for degradation of dangerous dyes.
Journal of Environmental Biology 12/2008; 29(6):831-6. · 0.64 Impact Factor
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ABSTRACT: FtsZ plays an important role in bacterial cell division by polymerizing to form the Z ring at the site of cytokinesis. Phytochemicals are known to disrupt bacterial cell division through inhibition of FtsZ assembly. In the present study phytochemicals like eugenol, trans-cinnamic acid, 4-formyl cinnamic acid, naringenin and caffeic acid were were tested for their potential to inhibit cell division. Effect of these antimicrobial compounds on the growth of E. coli was determined and the inhibition of FtsZ assembly in vitro was investigated. The present study revealed trans-cinnamic acid as the most potent inhibitor of FtsZ assembly.
Indian journal of experimental biology 12/2008; 46(11):783-7. · 1.29 Impact Factor
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ABSTRACT: The ever increasing problem of antibiotic resistance necessitates a search for new drug molecules that would target novel proteins in the prokaryotic system. FtsZ is one such target protein involved in the bacterial cell division machinery. In this study, we have shown that berberine, a natural plant alkaloid, targets Escherichia coli FtsZ, inhibits the assembly kinetics of the Z-ring, and perturbs cytokinesis. It also destabilizes FtsZ protofilaments and inhibits the FtsZ GTPase activity. Saturation transfer difference NMR spectroscopy of the FtsZ-berberine complex revealed that the dimethoxy groups, isoquinoline nucleus, and benzodioxolo ring of berberine are intimately involved in the interaction with FtsZ. Berberine perturbs the Z-ring morphology by disturbing its typical midcell localization and reduces the frequency of Z-rings per unit cell length to half. Berberine binds FtsZ with high affinity ( K D approximately 0.023 microM) and displaces bis-ANS, suggesting that it may bind FtsZ in a hydrophobic pocket. Isothermal titration calorimetry suggests that the FtsZ-berberine interaction occurs spontaneously and is enthalpy/entropy-driven. In silico molecular modeling suggests that the rearrangement of the side chains of the hydrophobic residues in the GTP binding pocket may facilitate the binding of the berberine to FtsZ and lead to inhibition of the association between FtsZ monomers. Together, these results clearly indicate the inhibitory role of berberine on the assembly function of FtsZ, establishing it as a novel FtsZ inhibitor that halts the first stage in bacterial cell division.
Biochemistry 04/2008; 47(10):3225-34. · 3.42 Impact Factor
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ABSTRACT: Cinnamaldehyde is a natural product from spices that inhibits cell separation in Bacillus cereus. Cell division is regulated by FtsZ, a prokaryotic homolog of tubulin. FtsZ assembles into the Z-ring at the site of cell division. Here, we report the effect of cinnamaldehyde on FtsZ and hence on the cell division apparatus. Cinnamaldehyde decreases the in vitro assembly reaction and bundling of FtsZ. It is found that cinnamaldehyde perturbs the Z-ring morphology in vivo and reduces the frequency of the Z ring per unit cell length of Escherichia coli. In addition, GTP dependent FtsZ polymerization is inhibited by cinnamaldehyde. Cinnamaldehyde inhibits the rate of GTP hydrolysis and binds FtsZ with an affinity constant of 1.0+/-0.2 microM(-1). Isothermal titration calorimetry reveals that binding of cinnamaldehyde to FtsZ is driven by favorable enthalpic interactions. Further, we map the cinnamaldehyde binding region of FtsZ, using the saturation transfer difference-nuclear magnetic resonance and an in silico docking model. Both predict the cinnamaldehyde binding pocket at the C terminal region involving the T7 loop of FtsZ. Our results show that cinnamaldehyde binds FtsZ, perturbs the cytokinetic Z-ring formation and inhibits its assembly dynamics. This suggests that cinnamaldehyde, a small molecule of plant origin, is a potential lead compound that can be developed as an anti-FtsZ agent towards drug design.
Biochemical Pharmacology 10/2007; 74(6):831-40. · 4.70 Impact Factor
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ABSTRACT: The assembly and bundling of FtsZ protofilaments play an important role during bacterial cell division. Deuterium oxide (D2O) is known to have strong stabilization effects on the assembly dynamics of several proteins including tubulin, a homologue of FtsZ. Here, we found that D2O enhanced the light-scattering intensity of the assembly reaction, increased sedimentable polymer mass, and induced bundling of FtsZ protofilaments. D2O also increased the stability of FtsZ polymers under challenged GTP conditions and suppressed dilution-induced disassembly of protofilaments. D2O enhances the assembly parameters of FtsZ and microtubules albeit differently. For example, D2O induced bundling of FtsZ protofilaments, whereas it did not induce bundling of microtubules in vitro. In addition, D2O strongly suppressed the GTP hydrolysis rate of microtubules, but it had no effect on the initial rate of GTP hydrolysis of the FtsZ assembly. D2O (80%) also increased the helical content of FtsZ by 25% compared to the helical content of FtsZ in aqueous buffer. D2O was shown to reduce the binding of 4,4'-dianilino-1,1'-binaphthyl-5,5'-disulfonic acid (bis-ANS) to tubulin. In contrast, we found that D2O strongly enhanced the binding of bis-ANS to FtsZ. The results indicated that D2O promotes assembly and bundling of FtsZ protofilaments by increasing hydrophobic interactions between the protofilaments. The results also suggest that the phosphate release rather than the on-site GTP hydrolysis is the rate-limiting step of the GTP turnover reaction.
Proteins Structure Function and Bioinformatics 01/2006; 61(4):1101-10. · 3.39 Impact Factor
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ABSTRACT: The cysteine residues of yeast alcohol dehydrogenase (YADH) were covalently modified by N-(1-pyrenyl) maleimide (PM). A maximum of 3.4 cysteines per YADH monomer could be modified by PM. The secondary structure of PM-YADH was found to be similar to that of the native YADH using far-UV circular dichroism. The covalent modification of YADH by PM inhibited the enzymatic activity indicating that the active site of the enzyme was altered. PM-YADH displayed maximum excimer fluorescence at an incorporation ratio of 2.6 mol of PM per monomeric subunit of YADH. Nucleotide adenine dinucleotide (NAD) divalent zinc and ethanol reduced the excimer fluorescence of PM-YADH indicating that these agents induce conformational changes in the enzyme. Guanidinium hydrochloride (GdnHCl)-induced unfolding of YADH was analyzed using tryptophan fluorescence, pyrene excimer fluorescence and enzymatic activity. The unfolding of YADH was found to occur in a stepwise manner. The loss of enzymatic activity preceded the global unfolding of the protein. Further, changes in tryptophan fluorescence with increasing GdnHCl suggested that YADH was completely unfolded by 2.5 M GdnHCl. Interestingly, residual structures of YADH were detected even in the presence of 5 M GdnHCl using the excimer fluorescence of PM-YADH.
Photochemistry and Photobiology 82(2):480-6. · 2.41 Impact Factor
