Life Sciences Commons^™

Elucidation Of The Players And Events Regulating The First Meiotic Division In Mouse Spermatocytes, Amy Lynn Inselman

Doctoral Dissertations

Meiosis is the process that ensures the continued propagation of new organisms and is a source of genetic variability within a population. During meiotic prophase many dynamic rearrangements occur in the nucleus of the cell. These rearrangements include homologous chromosome pairing, recombination, synaptonemal complex breakdown, chromosome condensation and spindle assembly. The regulatory mechanisms behind these complex processes at the G2/MI transition have not been completely elucidated, preventing our complete understanding of the processes. The purpose of this work is to provide new insight to the events and players involved in the regulation of the G2/MI transition in mouse spermatocytes.

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Identifying The Catalytic And Ligand Binding Roles Of Active Site Residues In Homotetrameric R67 Dihydrofolate Reductase, Michael Brad Strader

Doctoral Dissertations

R67 dihydrofolate reductase (DHFR) is a novel protein that confers clinical resistance to trimethoprim (TMP). Surprisingly, this R-plasmid encoded enzyme does not share homology with chromosomal DHFR. Recently a high resolution crystal structure of R67 DHFR has been solved. From this structure, R67 DHFR is a homotetramer that possesses exact 222 symmetry and a single active site pore that traverses the length of the protein (Narayana et al., 1995). Although this symmetry implies that four symmetry related binding sites must exist for each substrate, isothermal titration calorimetry studies indicate only two molecules bind. Three possible combinations of bound ligands have …