The present work reports the synthesis and characterization of nanostructured poly (o-toluidine) (POT) reinforced epoxy-siloxane (ES) composite resins. The structural elucidation was carried out using FT-IR and UV-visible spectrometry. The FT-IR analysis confirmed the interaction between NH group of the POT and the OH group of ES via strong hydrogen bonding. The UV-visible spectra of POT/ES composites revealed a blue shift of 100 nm in the polaronic transition peak observed at 600 nm in pristine POT, which was attributed to the restriction in the delocalization of polarons in the POT chains due to electrostatic interaction via hydrogen bonding. The nanosize of POT and its dispersion in the ES matrix was confirmed by X-ray diffraction (XRD) and transmission electron microscopy studies. The particle size was found from 15-35 nm. The morphological studies confirmed the formation of a nanocomposite where POT appeared to act as reinforcing agent in the ES matrix. XRD showed the semi-crystalline nature of POT/ES nanocomposites. The conductivities of POT and its nanocomposites were 10 -3 -10 -4 S/cm at 30°C. The thermal stability increased with an increase in the loading of POT in ES. The nanocomposites revealed good physico-chemical and physicomechanical characteristics, which suggests their potential application as corrosion protective coatings.
In the present study, we elucidated the effect of potassium salts on alkali denatured hen egg white lysozyme (EC 3.2.1.17) using intrinsic/extrinsic fluorescence as well circular dichroism (CD) spectroscopic methods. Intrinsic fluorescence studies revealed that various potassium salts mediate stabilization of lysozyme against alkali denaturation. Far and near UV CD spectrum studies, showed that 2M KCl induced appreciable amount of secondary structure with minimum tertiary contacts in lysozyme at pH 12.6. Acrylamide quenching studies suggest that at pH 12.6, the presence of 2M KCl causes reduced accessibility of the quencher to tryptophan residues of the protein presumably because of its compact conformation. In summary, the results of present study suggest that lysozyme attains a compact folded intermediate with molten globule like characteristics at alkaline pH in presence of potassium chloride.
RNA biogenesis and mRNA transport are an intricate process for every eukaryotic cell. SAGA, a transcriptional coactivator and TREX-2 are the two major complexes participate in this process. Sus1 is a transcription export factor and part of both the SAGA and the TREX-2 complex. The competitive exchange of Sus1 molecule between SAGA and TREX-2 complex modulates their function which is credited to structural plasticity of Sus1. Here, we portray the biophysical characterization of Sus1 from S. cerevisiae. The recombinant Sus1 is a α-helical structure which is stable at various pH conditions. We reported the α-helix to βsheet transition at the low pH as well as at high pH. Sus1 showed 50% reduction in the fluorescence intensity at pH-2 as compared to native protein. The fluorescence studies demonstrated the unfolding of tertiary structure of the protein with variation in pH as compared to neutral pH. The same results were obtained in the ANS binding and acrylamide quenching studies. Similarly, the secondary structure of the Sus1 was found to be stable till 55% alcohol concentration while tertiary structure was stable up to 20% alcohol concentration. Further increase in the alcohol concentration destabilizes the secondary as well as tertiary structure. The 300 mM concentration of ammonium sulfate also stabilizes the secondary structure of the protein. The structural characterization of this protein is expected to unfold the process of the transportation of the mRNA with cooperation of different proteins.
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