C-13 NMR relaxation studies on cartilage and cartilage components

We have investigated the molecular motions of polysaccharides of bovine nas al and pig articular cartilage by measuring the C-13 NMR relaxation times ( T-1 and T-2). Both types of cartilage differ significantly towards their co llagen/glycosaminoglycan ratio, leading to different NMR spectra. As chondr oitin sulfate is the main constituent of cartilage, aqueous solutions of re lated poly- and monosaccharides (N-acetylglucosamine and glucuronic acid) w ere also investigated. Although there are only slight differences in T-1 re laxation of the mono- and the polysaccharides, T-2 decreases about one orde r of magnitude, when glucuronic acid or N-acetylglucosamine and chondroitin sulfate are compared. It is concluded that the ring carbons are motion-res tricted primarily by the embedment in the rigid pyranose structure and, thu s, additional limitations of mobility do not more show a major effect. Sign ificant differences were observed between bovine nasal and pig articular ca rtilage, resulting in a considerable line-broadening and a lower signal to noise ratio in the spectra of pig articular cartilage. This is most likely caused by the higher collagen content of articular cartilage in comparison to the polysaccharide-rich bovine nasal cartilage. (C) 2000 Elsevier Scienc e Ltd. All rights reserved.