Biennial Report 2005-2007 - Saha Institute of Nuclear Physics

214 Biennial Report 2005-07active and structural sites leading to disruption of the oligomeric enzyme. It culminates in the lossof the enzyme activity. We have demonstrated the colocalization of the antibiotic and the enzymein the cytoplasmic region of Hep G2 cell, thereby supporting the validity of our proposition aboutintracellular mode of action of these anibiotics.P Grihanjali DeviBP6.1.4.2 Mechanism of transcription by T7 RNA polymeraseAs a sequel to our earlier report that the dye, cibacron blue binds to the enzyme at the twobinding sites for GTP we have attempted to locate the binding sites for the substrate GTP. Bymeans of isothermal calorimetry and docking calculations we mapped the bindng sites partially andelaborated the binding energetics for the association of the dye with the enzyme.Sudipta Pal, Rahul BanrejeeBP6.1.4.3 Effect of DNA binding antibiotics upon chromatin structureWe have examined the effect of a DNA binding plant alkaloid, sanguinarine, upon the structureof chromatin and nucleosome. Like other antibiotics, such as mithramycin and chromomycin, thiscompound induces chromatin aggregation and nucleosomal instability leading to DNA release. Wehave also done extensive thermodynamic studies to understand the energetics of their associationwith chromatin and nucleosome. Our objective is to detect thermodynamic signature of structuralalterations in chromatin and nucleosome induced by the small DNA-binding molecu:w les.Suman Kalyan Pradhan, Parijat Majumder, TK Kundu, Dipak DasguptaBP6.1.4.4 Self Aggregation of the drug MithramycinThe anionic form of the aureolic acid antibiotic Mithramycin undergoes self-association to formtetramer via the initial formation of dimer from monomer. The notable feature of the aggregationis that it is mediated by the carbohydrate moieties in the antibiotic, hitherto unreported for carbohydratecontaining antibiotics.Shibojyoti Lahiri, Parijat Majumder, P Grihanjali Devi, Dipak DasguptaBP6.1.5 Cellular & Molecular Biology6.1.5.1 Study of the survival pathways, which lead to the inhibition of apoptosis inV79 fibroblasts after environmental stressThis study was initiated in 2001 to investigate the roles of MAP kinase family enzymes (ERK, P38MAPK and JNK) , and the PI3 kinase -Akt pathway in the inhibition of apoptosis/greater survival