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dc.contributor.advisorChairperson, Graduate Committee: John W. Peters.en
dc.contributor.authorSarma, Ranjana.en
dc.date.accessioned2013-06-25T18:40:47Z
dc.date.available2013-06-25T18:40:47Z
dc.date.issued2009en
dc.identifier.urihttps://scholarworks.montana.edu/xmlui/handle/1/2179
dc.description.abstractThe studies presented in this thesis include studies of nucleotide-dependent conformations of the electron donor protein in nitrogenase and dark-operative protochlorophyllide reductase (DPOR) characterized using small-angle x-ray scattering and x-ray diffraction methods. Nitrogen fixation and chlorophyll synthesis are involved in the reduction of high energy bonds under physiological conditions. Both make use of elegant reaction mechanisms made possible by complex enzyme systems which are evolutionarily related. Nitrogenase reduces nitrogen to ammonia and is a two-component metalloenzyme composed of Fe protein and MoFe protein. For nitrogen reduction, the Fe protein and MoFe protein associate and dissociate in a manner concomitant with hydrolysis of at least two MgATP molecules and enables the concomitant transfer of at least one electron from Fe protein to MoFe protein. During chlorophyll biosysnthesis, the rate limiting step is catalyzed by a two-component metalloenzyme called DPOR. The two components of DPOR are BchL and BchNB proteins and these share high level of sequence similarity with the Fe protein and the MoFe protein, respectively. Based on this sequence similarity and biochemical data available, it is proposed that the reaction mechanism is similar to nitrogenase mechanism in which the components of DPOR associate and dissociate in a nucleotide dependent manner, to enable intercomponent electron transfer. Fe protein and BchL present as unique examples of proteins that couple nucleotide dependent conformational change to enable electron transfer for high energy bond reduction. The present studies have been directed at studying the low resolution studies of MgATP-bound wild-type Fe protein and its comparison to the structure of the proposed mimic, i.e, L127 Delta Fe protein. The studies presented show evidence of the MgATP-bound wild-type Fe protein having a conformation very different from the L127 Delta Fe protein. The chapters also include detailed characterization of the structure of BchL in both MgADP bound and nucleotide-free states which offer detailed insights in the structure based mechanism of BchL, with primary focus on identifying key residues involved in componenet docking and in electron transfer. Together, the studies on the Fe protein and BchL have furthered our understanding of mechanism of electron transfer in these complex enzyme systems.en
dc.language.isoengen
dc.publisherMontana State University - Bozeman, College of Letters & Scienceen
dc.subject.lcshNitrogenase.en
dc.subject.lcshIron proteins.en
dc.subject.lcshSmall-angle x-ray scattering.en
dc.titleInvestigations of nucleotide-dependent electron transfer and substrate binding in nitrogen fixation and chlorophyll biosynthesis
dc.typeDissertation
dc.rights.holderCopyright Ranjana Sarma 2009en
thesis.catalog.ckey1509298en
thesis.degree.committeemembersMembers, Graduate Committee: Brian Bothner; Joan Broderick; Robert K. Szilagyi; C. Martin Lawrenceen
thesis.degree.departmentChemistry & Biochemistry.en
thesis.degree.genreDissertationen
thesis.degree.namePhDen
thesis.format.extentfirstpage1en
thesis.format.extentlastpage147en
mus.identifier.categoryLife Sciences & Earth Sciences
mus.identifier.categoryChemical & Material Sciences
mus.relation.departmentChemistry & Biochemistry.en_US
mus.relation.universityMontana State University - Bozemanen_US


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