Studying Collagen with PyrATS: Pyrene-Appended Trimeric Systems

"Collagens are a family of triple-helical structural proteins that are ubiquitous in vertebrates. Improper folding of collagen can lead to disorders such as osteogenesis imperfecta , or ""brittle bone disease."" There is significant interest in understanding the factors that drive collagen folding and stability , but studying native collagens is difficult because they are hundreds of amino acids in length. This thesis describes a series of well-characterized (Pro-Hyp-Gly)7 model peptides which have been tagged at their N-termini with the fluorophore pyrene. When in close contact , pyrene units can form excimers that emit low-energy light. This allows for the study of several fundamental questions in collagen research using fluorescence spectroscopy , including concentration dependence , folding directionality , and local fraying , upon solutions that are significantly more dilute than those customarily used in circular dichroism (CD) experiments. Notably , for most of the peptides studied , there is agreement between the melting temperatures (Tm) obtained via fluorescence and CD techniques. In addition , the pyrene probes were found to provide a situational increase in thermal stability of triple helices.