The remarkable fidelity of most DNA polymerases depends on a series of early steps in the reaction pathway which allow the selection of the correct nucleotide substrate, while excluding all incorrect ones, before the enzyme is committed to the chemical step of nucleotide incorporation. The conformational transitions that are involved in these early steps are detectable with a variety of fluores...

Proteins exist as an ensemble of conformers that are distributed on free energy landscapes resembling folding funnels. While the most stable conformers populate low energy basins, protein function is often carried out through low-populated conformational states that occupy high energy basins. Ligand binding shifts the populations of these states, changing the distribution of these conformers. U...

This work presents the determination of a semiclassical conformational partition function for bioactive compounds. The proposed partition function includes the effect of the rotovibrational coupling and the conformational kinetic energy, through the rotovibrational G matrix. In addition, the model considers a relaxed potential that includes the effect of the nonconformational, internal, coordin...

Product releasing is an essential step of an enzymatic reaction, and a mechanistic understanding primarily depends on the active-site conformational changes and molecular interactions that are involved in this step of the enzymatic reaction. Here we report our work on the enzymatic product releasing dynamics and mechanism of an enzyme, horseradish peroxidase (HRP), using combined single-molecul...

We explored the conformational landscape of the proteinogenic amino acid serine [CH(2)OH CH(NH(2)) COOH] in the gas phase. Solid serine was vaporized by laser ablation, expanded in a supersonic jet, and characterized by Fourier transform microwave spectroscopy. In the isolation conditions of the jet there have been discovered up to seven different neutral (non-zwitterionic) structures of serine...

Free-energy landscape is an important quantity to study large-scale motions of a biomolecular system because it maps possible pathways for the motions. When the landscape consists of thermodynamically stable states (low-energy basins), which are connected by narrow conformational pathways (i.e., bottlenecks), the narrowness slows the inter-basin round trips in conformational sampling. This resu...

In addition to their capacity for template-directed 5' --> 3' DNA synthesis at the polymerase (pol) site, DNA polymerases have a separate 3' --> 5' exonuclease (exo) editing activity that is involved in assuring the fidelity of DNA replication. Upon misincorporation of an incorrect nucleotide residue, the 3' terminus of the primer strand at the primer-template (P/T) junction is preferentially t...

Protein conformational changes are commonly associated with the formation of protein complexes. The non-catalytic death effector domains (DEDs) mediate protein-protein interactions in a variety of cellular processes, including apoptosis, proliferation and migration, and glucose metabolism. Here, using NMR residual dipolar coupling (RDC) data, we report a conformational change in the DED of the ...

Estimation of protein stability is important for many reasons: first providing an understanding of the basic thermodynamics of the process of folding, protein engineering, and protein stability plays important role in biotechnology especially in food and protein drug design. Today, proteins are used in many branches, including industrial processes, pharmaceutical industry, and medical fields. A...

Single molecule fluorescence spectroscopy holds the promise of providing direct measurements of protein folding free energy landscapes and conformational motions. However, fulfilling this promise has been prevented by technical limitations, most notably, the difficulty in analyzing the small packets of photons per millisecond that are typically recorded from individual biomolecules. Such limita...