Biology; Chemistry and chemical biology; Chemical and biological engineering; Biomedical engineering
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Determination of the pKa of Glucuronic Acid and Heparin's Carboxyl Groups by 13C NMR, H.M. Wang, D. Loganathan, R.J. Linhardt, Biochemical Journal, 278, 689-695 (1991).
As part of our continuing studies on heparin, the present paper uses 13C-n.m.r. spectroscopy to examine the acidity of heparin's uronic acid carboxylate groups. Heparin contains three different uronic acids. In porcine mucosal heparin these account for approx. 91, 7 and 2 mol% of the total uronic acid residues. These are alpha-L-idopyranosyluronic acid 2-sulphate, beta-D-glucopyranosyluronic acid and alpha-L-idopyranosyluronic acid. The pKa values of their carboxylate groups were determined as 3.13 (using heparin), 2.79 (using heparin) and 3.0 (predicted by using model compounds) respectively. 18C-n.m.r. spectroscopy, performed at various pH values, provided a convenient method of simultaneously determining the pKa of multiple carboxylate groups, of similar acidity, within heparin D-Glucopyranosyluronic acid and heparin-derived di-, tetra- and hexa-saccharides were used as model compounds to determine pKa values of the different carboxy groups. The results suggested that molecular size had an effect on pKa. Unambiguous assignment of carboxy carbon resonances were accomplished through the use of two-dimensional n.m.r. spectroscopy. Finally, application of this method to the simplest model compound, D-glucopyranosyluronic acid, permitted the determination of the pKa of both its alpha- and beta-anomers.;
Biochemical Journal, 278, 689-695; Note : if this item contains full text it may be a preprint, author manuscript, or a Gold OA copy that permits redistribution with a license such as CC BY. The final version is available through the publisher’s platform.
The Linhardt Research Labs.; The Shirley Ann Jackson, Ph.D. Center for Biotechnology and Interdisciplinary Studies (CBIS);
The Linhardt Research Labs Online Collection; Rensselaer Polytechnic Institute, Troy, NY; https://harc.rpi.edu/;