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Accueil du site → Doctorat → Inde → 2007 → Molecular characterization of genes involved in drought responsive proteome of Legum

Jawaharlal Nehru University (2007)

Molecular characterization of genes involved in drought responsive proteome of Legum

Bhushan, Deepti

Titre : Molecular characterization of genes involved in drought responsive proteome of Legum Auteur : Bhushan, Deepti

Université de soutenance : Jawaharlal Nehru University

Grade : Doctor of Philosophy (PhD) 2007

The present thesis
Biochemical and biophysical evidences have firmly established the 14 filament model of the fiber made out of a double-stranded arrangement of Hb molecules similar to those found in the crystals of HbS. The fiber architecture is stabilized by two kinds of interactions, namely, intra-double strand (axial and lateral) and interdouble strand. While intra-double strand contacts of the crystal are preserved in the fiber, the inter-double strand contacts are unique to the fiber. As discussed above, the identity of many of these intermolecular contact residues are known from solution polymerization experiments of natural variants or mutant hemoglobins and HbS crystal structure. However, our present knowledge of intermolecular interaction in the HbS fiber is largely limited to the identity of the contact residues with little information on the interaction strength of individual contact residues. The effect of simultaneous perturbation of contact residues have been experimentally demonstrated for some sites but the mechanistic basis of additive or non-additive coupling between these interacting sites is far from clear. HbS fiber formation is a complex process that requires specific contacts, and presumably intricate interplay between several residues from both, a and , chains of the tetramer. Besides, the polymerization occurs only on in the deoxy state (’T’ state) of the HbS suggesting that quaternary conformational events are detrimental to the polymerization process. However studies of quaternary structure vis a vis HbS polymerization has not been carried out though the impact of quaternary structural constrains has been extensively analysed in the context of deciphering the mechanistic imperatives of hemoglobin allostery. In as much as the HbS polymerization is triggered by the acquisition of T structure, it is legitimate to conceive that perturbation of this quaternary state may have perceptible influence on kinetics and/or equilibrium of the polymerization reaction. The work described in this thesis concerns with the above aspects of HbS polymerization namely, (a) delineation of interaction-linkage (coupled interactions) between selected fibre contact residues, and (b) probing the role, if any, of the quaternary structural features ofthe HbS tetramer on the polymerization reaction.

Mots clés : Genes Drought responsive legume proteome

Présentation et version intégrale (Shodhganga)

Page publiée le 16 avril 2021