Binding of hyaluronate and chondroitin sulphate to liver endothelial cells

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Abstract
Hyaluronate is taken up and metabolized in liver endothelial cells by means of a receptor. To characterize the interaction with the receptor, two preparations of 3H-labelled hyaluronate, of Mr 4 .times. 105 and 6.4 .times. 106, and a series of hyaluronate oligosaccharides were bound to cultured liver endothelial cells at 7.degree. C. The dissociation constant varied between 4.6 .times. 10-6 M for an octasaccharide and 9 .times. 10-12 M for the largest polymer. The Mr-dependence for the series of oligosaccharides was explained by the increased probability of binding due to the repetitive sequence along the chain. The high affinity of high-Mr hyaluronate for the receptor could also be mainly ascribed to this effect, which rules out any major contribution of co-operative multiple-site attachment to the cell surface. Each liver endothelial cell can bind 105 oligosaccharides, about 104 molecules with Mr 4 .times. 105 and about 103 molecules with Mr 6.4 .times. 106. This is explained by mutual exclusion of large molecules from the cell surface. Chondroitin sulfate is also bound to liver endothelial cells. Inhibition studies showed that it binds to the same receptor as hyaluronate and with an affinity that is about 3-fold higher than that of hyaluronate of the same degree of polymerization.