Journal of BioScience and Biotechnology (JBB)

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https://doi.uni-plovdiv.bg/handle/store/2
p-ISSN: 1314-6238 / e-ISSN: 1314-6246

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Browsing Journal of BioScience and Biotechnology (JBB) by Author "Abraham, Suja"

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    Conformational changes induced by Mg2+ on the multiple forms of glutamine synthetase from Bacillus brevis Bb G1
    (Plovdiv University Press “Paisii Hilendarski”, 2013-09-12) Abraham, Suja
    Conformational changes play an important role in the function of proteins. Glutamine synthetase, an important enzyme of nitrogen metabolism, was purified under sporulating (GSala) and non-sporulating (GSpyr) conditions and the effect of Mg2+ on these multiple forms was studied by fluorescence spectroscopy to detect possible conformational changes that occur in the presenceof Mg2+. The substantial changes in the fluorescence emission maximum, fluorescence intensity and lifetime that occur in the presence of different concentrations of Mg2+, indicated major changes in molecular conformations in both forms of this enzyme. The fluorescent changes produced by the effect of Mg2+ in GSala was much more prominent than in GSpyr. These observations strongly support the possibility that GSala and GSpyr undergoes a conformational change on binding with Mg2+.
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    Fluorescence study on ligand induced conformational changes of glutamine synthetase from Bacillus brevis Bb G1 under sporulating conditions
    (Plovdiv University Press “Paisii Hilendarski”, 2015-02-18) Abraham, Suja
    Glutamine synthetase, an important enzyme of nitrogen metabolism, was purified under sporulating conditions (GSala). The effect of ligands on the tryptophan fluorescence of the purified enzyme GSala was investigated. With increasing concentrations of L-glutamine in GSala, a blue shift in emission maximum with an increase in fluorescence intensity and decrease in life times were observed compared to the emission maximum, fluorescence intensity and life times of GSala. With increasing concentrations of glycine in GSala, a shift in emission maximum, change in fluorescence intensity and change in lifetimes were observed compared to the emission maximum, fluorescence intensity and life times of GSala. These observations strongly support the possibility that GSala undergoes a conformational change on binding with ligands and each ligand produced different conformational changes in GSala. Also, different concentrations of each ligand produced different protein conformations in the enzyme GSala.