Abstract
The relaxation rate R = πΔν1/2 of the quadrupolar 23Na nucleus was measured at pH ≈ 7 using a 200 MHz NMR spectrometer with a view to observe the interaction between hyaluronan and its natural counterion Na+ and the bications Ca++, Mg++ and Cu++.
An interpretation of our results, by means of the “entropy of fluctuations” concept of Na+, is presented.
We show that Cu++ ions are more effective than Ca++ and Mg++. A possible model of com- plexation of Cu++ in a cage formed by the 1–4 glycosidic bond, the carboxylate side-chain and the acetoamide side-chain is proposed, according to electrostatic potential computations using the ZINDO1 quantum semi empirical method.