Singh, C., et al., Direct Evidence of Imino Acid–Aromatic Interactions in Native Collagen Protein by DNP-Enhanced Solid-State NMR Spectroscopy. The Journal of Physical Chemistry Letters, 2014. 5(22): p. 4044-4048.
Aromatic amino acids (AAAs) have rare presence (?1.4% abundance of Phe) inside of collagen protein, which is the most abundant animal protein playing a functional role in skin, bone, and connective tissues. The role of AAAs is very crucial and has been debated. We present here experimental results depicting interaction of AAAs with imino acids in a native collagen protein sample. The interaction is probed by solid-state NMR (ssNMR) spectroscopy experiments such as 1H?13C heteronuclear correlation (HETCOR) performed on a native collagen sample. The natural abundance 13C spectrum was obtained by dynamic nuclear polarization (DNP) sensitivity enhancement coupled with ssNMR, providing 30-fold signal enhancement. Our results also open up new avenues of probing collagen structure/dynamics closest to the native state by ssNMR experiments coupled with DNP.