jp511288g_si_001.pdf (2.29 MB)
Predominant Role of Water in Native Collagen Assembly inside the Bone Matrix
journal contribution
posted on 2015-01-08, 00:00 authored by Ratan
Kumar Rai, Chandan Singh, Neeraj SinhaBone
is one of the most intriguing biomaterials found in nature
consisting of bundles of collagen helixes, hydroxyapatite, and water,
forming an exceptionally tough, yet lightweight material. We present
here an experimental tool to map water-dependent subtle changes in
triple helical assembly of collagen protein in its absolute native
environment. Collagen being the most abundant animal protein has been
subject of several structural studies in last few decades, mostly
on an extracted, overexpressed, and synthesized form of collagen protein.
Our method is based on a 1H detected solid-state nuclear
magnetic resonance (ssNMR) experiment performed on native collagen
protein inside intact bone matrix. Recent development in 1H homonuclear decoupling sequences has made it possible to observe
specific atomic resolution in a large complex system. The method consists
of observing a natural-abundance two-dimensional (2D) 1H/13C heteronuclear correlation (HETCOR) and1H double quantum–single quantum (DQ-SQ) correlation ssNMR
experiment. The 2D NMR experiment maps three-dimensional assembly
of native collagen protein and shows that extracted form of collagen
protein is significantly different from protein in the native state.
The method also captures native collagen subtle changes (of the order
of ∼1.0 Å) due to dehydration and H/D exchange, giving
an experimental tool to map small changes. The method has the potential
to be of wide applicability to other collagen containing biomaterials.