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Molecular Level Understanding of Biological Systems with High Motional Heterogeneity in Its Absolute Native State

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journal contribution
posted on 08.09.2016, 00:00 by Chandan Singh, Rudra N. Purusottam, Akhila Viswan, Neeraj Sinha
Biological tissues possessing motional heterogeneity are difficult to comprehend at atomic level in their native state. Some of these tissues play crucial roles in support and movement of the body. Articular cartilage is one such tissue exemplified with highly mobile glycosaminoglycans (GAGS, correlation time ∼10–9s) and relatively rigid collagen protein (correlation time ∼10–6 s). Simultaneous study of both the components at atomic level is challenging and requires different sets of solid state nuclear magnetic resonance (ssNMR) experiments for mobile and rigid parts. Additionally, it is hard to get any quantitative information as one 13C one pulse experiment is time-consuming. We present here a 13C ssNMR experiment with complete molecular characterization of cartilage organic components in its native state. We achieved this by employing heteronuclear Overhauser enhancement with equilibration of magnetization by low power irradiation. Complete 13C resonances from GAGS and collagen were identified simultaneously with 2–6 times sensitivity enhancement. We are also providing a method to characterize GAGs (qualitatively and quantitatively) in native state thereby increasing its applicability in disease conditions where GAGS is degraded. This method is not only applicable to biological tissues such as cartilage but also to understand ultrastructural details of hydrogels and other motional heterogeneous biomaterials used in cartilage tissue engineering.