Resolving Nitrogen-15 and Proton Chemical Shifts for the Mobile Segments of Elastin with Two-Dimensional NMR Spectroscopy

In this study, oneand two-dimensional NMR experiments are applied to uniformlyN-enriched synthetic elastin, a recombinant human tropoelastin that has been crosslinked to form an elastic hydrogel. Hydrated elastin is characterized by large segments that undergo “liquidlike” motions that limit the efficiency of cross-polarization. The refocused INEPT experiment is used to target these extensive, mobile regions of this protein. Numerous peaks are detected in the backbone amide region of the protein, and their chemical shifts indicate the completely unstructured, “random coil” model for elastin is unlikely. Instead, more evidence is gathered that supports a characteristic ensemble of conformations in this rubberlike protein.