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Papers by T. Balasubramanian

The aim of the present study was to isolate a thermostable and alkaline tolerant xylanase produci... more The aim of the present study was to isolate a thermostable and alkaline tolerant xylanase producing strain from an estuarine environment, and to produce, purify and characterize the enzyme. The bacterium, Bacillus subtilis isolated from the estuarine environment was grown in shake flasks to derive the optimum culture conditions and also cultured in lab scale fermentor to obtain more xylanase. Maximum enzyme production (128 U/mL) was recorded in stationary phase (36 h) of the culture. The enzyme was purified using ammonium sulphate precipitation (60% saturation), followed by DEAE-cellulose column chromatography. The enzyme was optimally active at 55 o C and pH 9.0. Influence of metal ions on enzyme activity revealed that, Fe 2+ , Ca 2+ , and Mg 2+ greatly enhanced the enzyme activity to 238, 148, 208 U/mL, respectively; whereas Hg 2+ (0 U/mL) and EDTA (18 U/mL) strongly inhibited the enzyme activity. Based on the results obtained, xylanase isolated in this study may be useful in pulp pre-bleaching process to remove the hemicelluloses. The use of thermostable alkaline tolerant xylanase for enzyme assisted pulp bleaching could greatly reduce the need for pH and temperature readjustment, thus offering enormous technical and economic advantages.

Bangladesh Journal of Pharmacology, 2008

Physical Review Letters, 1998

Parasitology Research, 2012

In this study, a massive infestation of the sea snake Enhydrina schistosa by the cymothoid isopod... more In this study, a massive infestation of the sea snake Enhydrina schistosa by the cymothoid isopod Nerocila serra, commonly parasitizing fishes, is reported for the first time from India. This isopod was found attached on the different parts of the body of the snake. According to the month, the parasitic prevalence ranged from 30.8 to 55.3%, increasing during the monsson period. It was higher in female than in male snakes.

Nature Communications, 2012

The Journal of Organic Chemistry, 2001

Chlorin building blocks incorporating a geminal dimethyl group in the reduced ring and synthetic ... more Chlorin building blocks incorporating a geminal dimethyl group in the reduced ring and synthetic handles in specific patterns at the perimeter of the macrocycle are expected to have utility in biomimetic and materials chemistry. A prior route employed condensation of a dihydrodipyrrin (Western half) and a bromodipyrromethane-monocarbinol (Eastern half), followed by oxidative cyclization of the putative dihydrobilene-a to form the meso-substituted zinc chlorin in yields of ∼10%. The limited stability of the dihydrodipyrrin precluded study of the chlorin-forming process. We now have refined this methodology. A tetrahydrodipyrrin Western half (2,3,4,5-tetrahydro-1,3,3-trimethyldipyrrin) has been synthesized and found to be quite stable. The condensation of the Western half and an Eastern half (100 mM each) proceeded smoothly in CH 3 CN containing 100 mM TFA at room temperature for 30 min. The resulting linear tetrapyrrole, a 2,3,4,5tetrahydrobilene-a, also is quite stable, enabling study of the conversion to chlorin. Refined conditions for the oxidative cyclization were found to include the following: the tetrahydrobilene-a (10 mM), AgTf (3-5 molar equiv), Zn(OAc) 2 (15 molar equiv), and 2,2,6,6-tetramethylpiperidine (15 molar equiv) in CH 3 CN at reflux exposed to air for 4-6 h, affording the zinc chlorin. The chlorinforming process could be implemented in either a two-flask process or a one-flask process. The two-flask process was applied to form six zinc chlorins bearing substituents such as pentafluorophenyl, 3,5-di-tert-butylphenyl, TMS-ethyl benzoate, iodophenyl, or ethynylphenyl (deprotection of the TMS-ethynyl group occurred during the oxidative cyclization process). The stepwise yields (isolated) for the condensation and oxidative cyclization processes forming the tetrahydrobilene and zinc chlorin were 32-72% and 27-62%, respectively, giving overall yields of zinc chlorin from the Eastern and Western halves of 12-45%. Taken together, the refinements introduced enable 100-mg quantities of chlorin building blocks to be prepared in a facile and rational manner.

Journal of Molecular Biology, 1983

We report here the 500MHz 1H nuclear magnetic resonance spectra of Alamethicin, an ieosapeptide a... more We report here the 500MHz 1H nuclear magnetic resonance spectra of Alamethicin, an ieosapeptide antibiotic isolated from Trichoderma viride, in methanol, water and methanol/water mixtures. At this frequency, resonances from all the protons are well-resolved in methanol and may be assigned unambiguously. Spectral assignments were made using two-dimensional spin-echo correlated spectroscopy and by spin-deeoupling experiments. The amide coupling constants (J,~m, cH) facilitated conformational predictions, which were confirmed in part by two-dimensional nuclear Overhauser experiments. On the basis of these data, we propose a secondary structure for Alamethicin that is a-helical toward the N terminus and extended fl-sheet at the C-terminal end. This structure is consistent with earlier circular dichroism measurements (MeMullen et al., 1971), infrared attenuated total reflection spectroscopy studies and proton exchange data .

Current Applied Physics, 2011

... The resistivity value showed a minimum of 4.2 × 10 −3 Ω cm and the grain size reached a maxim... more ... The resistivity value showed a minimum of 4.2 × 10 −3 Ω cm and the grain size reached a maximum of 125 nm for the ITO film deposited at 250 W. The XPS, EDAX and AFM results revealed the formation of stoichiometric and smooth ITO films, which contained nano-sized grains ...

Acta Crystallographica Section E Structure Reports Online, 2006

ABSTRACT

Journal of Ecological Engineering, 2015