Studying Collagen with PyrATS: Pyrene-Appended Trimeric Systems

Abstract

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.