Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: August 18, 2004
Publication Date: August 18, 2004
Citation: Barone, J.R., Schmidt, W.F. 2004. Molecular conformational changes in cartilage studied with NMR spectroscopy [abstract]. Polymer Networks Conference, Bethesda, MD, Aug. 16-18, 2004. Paper No. P02.
The "free swelling" experiment for cartilage is reproduced and swelling effects monitored using 1H nuclear magnetic resonance (NMR) spectroscopy. Meniscus cartilage from the bovine stifle joint is equilibrated in NaCl solutions of varying concentration. The 1H NMR spectrum of cartilage shows a peak characteristic of glycine, the most abundant amino acid in the collagen phase of cartilage, and a peak characteristic of the N-acetyl (N-Ac) methyl groups on the glycosaminoglycan (GAG) molecules. As a function of increasing NaCl concentration, the peak characteristic of GAG increases in intensity and width. In addition, the GAG peak changes in chemical shift, d (ppm). Concurrently, the collagen peak also experiences a chemical shift change. The changes in shape and chemical shift of the GAG characteristic peak suggest that it undergoes a conformational change as a function of increasing NaCl concentration. This results from screening of the negatively charged GAG molecules. In turn, the intimate connection between the collagen and proteoglycan (PG) complex causes the collagen network to change conformation as well. It is found that the change in chemical shift of the cartilage molecules has a similar scaling as the change in height of cartilage during a free swelling experiment when both are plotted as a function of added NaCl concentration.