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dc.contributor.advisorDaniel S. Kemp.en_US
dc.contributor.authorArtin, Erin Jelenaen_US
dc.contributor.otherMassachusetts Institute of Technology. Dept. of Chemistry.en_US
dc.date.accessioned2007-02-20T15:07:29Z
dc.date.available2007-02-20T15:07:29Z
dc.date.copyright2006en_US
dc.date.issued2006en_US
dc.identifier.urihttp://hdl.handle.net/1721.1/35920
dc.descriptionThesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2006.en_US
dc.descriptionThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.en_US
dc.descriptionVita.en_US
dc.descriptionIncludes bibliographical references.en_US
dc.description.abstractRibonucleotide reductases (RNRs) catalyze the conversion of nucleotides to deoxynucleotides, providing the monomeric precursors required for DNA replication and repair. The class I RNRs are found in many bacteria, DNA viruses, and all eukaryotes including humans, and are composed of two homodimeric subunits: R1 and R2. RNR from Escherichia coli (E. coli ) serves as the prototype of this class. R1 has the active site where nucleotide reduction occurs, and R2 contains the diferric-tyrosyl radical (Y · ) cofactor essential for radical initiation on R1. The rate-determining step in E. coli RNR has recently been shown to be a physical step prior to generation of the putative thiyl radical (S · ) on C439. Thus, the chemistry of nucleotide reduction is kinetically invisible, which has precluded detection of intermediates in the reduction process with the normal substrate. Perturbation of the system using mechanism-based inhibitors and site-directed mutants of R1 and R2 has provided the bulk of the insight into the reduction mechanism by inference.en_US
dc.description.abstract(cont.) The work described in this thesis makes use of two mechanism-based inhibitors, 20 - azido - 20 - deoxyuridine - 50 - diphosphate (N3UDP) and 20 - deoxy - 20,20 - difluorocytidine - 50 - diphosphate (dFdCDP), and one active site mutant, E441Q R1, to further our understanding of the catalytic capabilities of RNR. The results provide strong support for a 30 - ketodeoxynucleotide intermediate postulated to lie on the normal reduction pathway, as well as for the elimination of nitrogenous base in the active site of R1 during inhibition. The studies further show that under physiologically relevant reducing conditions, inhibition of RNR by the clinically important nucleotide analog dFdCDP is a result of covalent modification. An essential part of these studies was the development of a robust, high-yielding enzymatic method for the selective 50 - phosphorylation of cytidine, 20 - deoxycytidine, 20 - deoxyuridine and their analogs that are not amenable to standard chemical phosphorylation methods.en_US
dc.description.statementofresponsibilityby Erin Jelena Artin.en_US
dc.format.extent164 p.en_US
dc.language.isoengen_US
dc.publisherMassachusetts Institute of Technologyen_US
dc.rightsM.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.en_US
dc.rights.urihttp://dspace.mit.edu/handle/1721.1/7582
dc.subjectChemistry.en_US
dc.titleMechanistic studies of the Class I ribonucleotide reductase from Escherichia colien_US
dc.typeThesisen_US
dc.description.degreeSc.D.en_US
dc.contributor.departmentMassachusetts Institute of Technology. Department of Chemistry
dc.identifier.oclc77530242en_US


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