We will continue to refine and extend UV resonance Raman spectroscopy (UVRR) as a sensitive, incisive technique for examining amide excited states, bio-molecular structure and function, and folding dynamics. We will use UVRR to examine the most important phenomena in protein folding such as the evolution of secondary structure and hydrophobic collapse. 1) We will use our recently discovered correlation between the amide III Raman band frequency and the Ramachandran Y angle to experimentally map the energy landscapes of proteins and peptides. We will use the T-jump UVRR methods pioneered in our lab to explore the peptide conformational dynamics that occur along the (un)folding reaction coordinates. We will measure, for the first time, the relative energies of protein conformational motifs and of their surface crossing conformational activation barriers. We will examine the evolution of secondary structure in response to temperature and solution environment alterations. 2) We will also examine cold denaturation in well defined nanogels of the homopolymer poly-N-isopropylacrylamide, which undergoes a temperature-driven volume phase transition similar to the cold denaturation phenomenon of proteins. We will utilize the understanding gained in these studies to explore the dramatic cold denaturation process in elastin, a biologically essential protein. Elastin's extensive cold denaturation process appears to be a consequence of its unique structure, which enables it to change volume without storage of the elastic energy that could lead to bond breakage. We will examine the coupling between elastin's hydrophobic collapse and its secondary structural evolution. 3) We will continue to develop and refine UV Raman instrumentation and methodologies to make this powerful spectroscopic technique more sensitive, more incisive and less expensive for use in biophysical and bio-analytical investigations. ? ? ?
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