Showing papers by "Kwang S. Kim published in 1990"
TL;DR: In this article, the cyclic O8 molecule has been studied using ab initio quantum mechanical methods and its molecular structures were fully optimized at levels of theory up to and including second-order perturbation theory (MP2) using a double zeta plus polarization basis set.
Abstract: The cyclic O8 molecule has been studied using ab initio quantum mechanical methods. Molecular structures were fully optimized at levels of theory up to and including second‐order perturbation theory (MP2) using a double zeta plus polarization basis set. Parallel theoretical studies were carried out for the valance isoelectronic S8 molecule, for which much experimental data exists. With double zeta plus polarization (DZ+P) self‐consistent‐field (SCF) theory vibrational frequencies and infrared and Raman intensities have been predicted. Cyclo‐O8 is considerably more stable than experimental O–O bond energies would suggest and is predicted to lie only 94 kcal/mol above four infinitely separated O2 molecules.
35 citations
TL;DR: This report studies the effects of internal deletions of the yeast transcriptional activator HAP1 on activity at two dissimilar DNA binding sites, upstream activation sequence 1 (UAS1) of CYC1 and CYC7, and shows that a zinc finger anchors DNA binding to both types of H AP1 sites.
Abstract: In this report we study the effects of internal deletions of the yeast transcriptional activator HAP1 (CYP1) on activity at two dissimilar DNA binding sites, upstream activation sequence 1 (UAS1) of CYC1 (iso-1-cytochrome c) and CYC7 (iso-2-cytochrome c). These deletions remove up to 1061 amino acids of the 1483-residue protein and bring the carboxyl-terminal acidic activation domain closer to the amino-terminal DNA-binding domain. Surprisingly, the deletions have opposite effects at the two sites; activity at UAS1 increases with deletion size, while activity at CYC7 decreases. The mutant with the largest deletion, mini-HAP1, has no measurable activity at CYC7 but binds normally to the site in vitro. In contrast, a protein with the DNA-binding domain of HAP1 fused to the acidic activation domain of GAL4 is active at both UAS1 and CYC7. These findings are discussed in the context of two models that suggest how the DNA sequence can alter the activity of the bound HAP1. In a separate experiment, we generate a mutation in the DNA-binding domain of HAP1 that requires the addition of zinc for binding to either UAS1 or CYC7 in vitro. This finding shows that a zinc finger anchors DNA binding to both types of HAP1 sites.
19 citations