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Download or read book Mechanistic Studies of the Class I Ribonucleotide Reductases from S. Cerevisiae and E. Coli written by Jie Ge and published by . This book was released on 2003 with total page 423 pages. Available in PDF, EPUB and Kindle. Book excerpt: (Cont.) The results of initial studies on the energetics of heterodimer formation using calorimetric techniques and site-directed mutagenesis are discussed in the context of the structures of Y2Y2, Y2Y4, and Y4Y4. As the discovery of a second R2 subunit is not unique to S. cerevisiae, the potential implication of the heterodimer in the regulation of deoxyribonucleotide synthesis is also considered. In the second part of this thesis, pre-steady state kinetics of the class I E. coli RNR is investigated using stopped-flow UV-visible spectroscopy and rapid chemical quench methods. These studies have led to a model in which the rate determining step in catalysis is a physical step prior to proton-coupled electron transfer (PCET), nucleotide reduction, and reverse PCET. These results provide a crucial first step in understanding radical initiation over 35 [angstroms].