Scientific Publications 2001
2001. "The Weak Interdomain Coupling Observed in the 70 kDa Subunit of Human Replication Protein A is Unaffected by ssDNA Binding." Nucleic Acids Research 29(15):3270-3276. Abstract Replication protein A (RPA) is a heterotrimeric, multifunctional protein that binds single-stranded DNA (ssDNA) and is essential for eukaryotic DNA metabolism. Using heteronuclear NMR methods we have investigated the domain interactions and ssDNA binding of a fragment from the 70 kDa subunit of human RPA (hRPA70). This fragment contains an N-terminal domain (NTD), which is important for hRPA70-protein interactions, connected to a ssDNA-binding domain (SSB1) by a flexible linker (hRPA701-3261). Correlation analysis of the amide 1H and 15 N chemical shifts was used to compare the structure of the NTD and SSB1 in hRPA701-326 with two smaller fragments that corresponded to the individual domains. High correlation coefficients verified that the NTD and SSB1 maintained their structures in hRPA701-326, indicating weak interdomain coupling. Weak interdomain coupling was also suggested by a comparison of the transverse relaxation rates for hRPA701-326 and one of the smaller hRPA70 fragments containing the NTD and the flexible linker (hRPA701-68).
2001. "A Temperature-Dependent Study of the Ozonolysis of Propene." Journal of Atmospheric Chemistry 40(3):231-245. Abstract The ozonolysis of propene has been investigated in a temperature controlled reaction chamber at 295, 260, and 230 K. Experiments were performed using a total zero air pressure of 760 Torr (STP) and propene/ozone reactant mixing ratios ranging from 2.3 to 23. ppmv. An analysis of FTIR spectra collected at the conclusion of each reaction revealed that methane was formed with a yield of 0.14 for all the temperatures investigated. In addition, the yield of HCHO decreased from 0.56 to 0.36 upon cooling from 295 to 230 K, whereas the yield of HCOOH increased from 0.11 to 0.53. Experiments were also performed using an excess of cyclohexane and it was found that the formaldehyde yield was 0.68 plus or minus 0.05 and 0.51 plus or minus 0.04 at 295 and 260 K, respectively. Finally, to more fully understand the reaction energies involved in product formation we have performed molecular orbital calculations of reactants, stable intermediates, and products.