INTERACTIONS BETWEEN DERMATAN SULFATE CHAINS .3. LIGHT-SCATTERING AND VISCOMETRY STUDIES OF SELF-ASSOCIATION

1. 1.Two dermatan sulphate preparations from pig skin, DS-18 and DS-36 with L-iduronic acid and D-glucuronic acid ratios of 90 : 10 and 75 : 25, respectively, were studied by light scattering and viscometry. 2. 2.In 0.15 M NaCl, both preparations yielded high particle weights (224 00 and 322 000, respectively) and viscometry at very low shear also yielded abnormally high intrinsic viscocities (108 and 128 ml/g, respectively). However, the two dermatan sulphate preparations affored 'monomeric' weight-average molecular weights (30 000 and 25 000) and normal intrinsic viscosities (49 and 35 ml/g) in 0.15 M KCl. Gel chromatography experiments further confirmed that dermatan sulphate chains have a tendency to self-associate in the presence of Na+. 3. 3.Dissociation of these 'superaggregates' in NaCl solutions could be accomplished by: (i) increasing the ionic strength to 0.5 M NaCl; (ii) increasing the shear rate to 10-20 s-1. 4. 4.When these 'superaggregates' were dissociated in 0.15 M NaCl, weight-average particle weights of 32 000 and 41 000 were found for DS-18 and DS-36 respectively. It is suggested that a further level of self-association, probably dimerisation, occurs in 'copolymeric' dermatan sulphates that have a high glucuronic acid content, as previously proposed (Fransson, L-Å. (1976) Biochim. Biophys. Acta 437, 106-115). © 1979.