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The acid mucopolysaccharides of cattle retina.

ABSTRACT: 1. Two polysaccharides were isolated from the interstitial matrix surrounding the photoreceptor cells of cattle retina. They were liberated from this region of the tissue in a soluble form after agitation of whole retinas in 0.9% sodium chloride. One, which comprises two-thirds of the polysaccharides present, is a hyaluronidase-sensitive ;half-sulphated' chondroitin sulphate containing uronic acid, galactosamine and sulphate in the molar proportions 1.27:1.0:0.54. The other is a hyaluronidase-resistant non-sulphated heteropolysaccharide for which the name sialoglycan is proposed. It contains galactose, glucosamine and sialic acid in the molar proportions 2.4:1.0:0.4. Both polysaccharides contain only small amounts of nitrogen in excess of the amount calculated from their amino sugar and sialic acid content. 2. A similar combination of mucopolysaccharides is associated with the pigment epithelial-cell layer but in quantities only one-fifth of those present in the adjacent matrix area. 3. The ease with which they are released into aqueous media is consistent with the assumption that they are present in the extracellular spaces in both of these tissue layers. 4. The retinal residue left after removal of the two soluble polysaccharides is rich in amino sugar- and sialic acid-containing polymers, which appear to be firmly bound to the tissue fragments. 5. About one-third of the sialic acid and one-tenth of the amino sugar could be extracted with chloroform-methanol. The components in this fraction were tentatively identified as gangliosides. 6. Digestion of the chloroform-methanol-insoluble residue with Pronase yielded as the principal product a heteropolysaccharide containing 16.5% of glucosamine, 24.3% of neutral sugar (galactose plus fucose) and 18.1% of sialic acid. This substance has been classified as a sialoglycan of composition similar to (but not identical with) that of the soluble one isolated from the matrix area of the tissue.

SUBMITTER: Berman ER

PROVIDER: S-EPMC1198771 | biostudies-other | 1968 Jun

REPOSITORIES: biostudies-other

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Project description:1. The effects of acid mucopolysaccharides and acid mucopolysaccharide-proteins on the size and rate of formation of fibril aggregates from collagen solutions in pH7.6 buffers were studied by turbidimetric and light-scattering methods. 2. Serum albumin, orosomucoid, methylated cellulose, chondroitin sulphate A and chondroitin sulphate C of molecular weight less than 20000, and hyaluronate of molecular weight less than 40000 did not influence rates of fibril formation. Chondroitin sulphate A, chondroitin sulphate C and hyaluronate of high molecular weight retarded the rate of fibril formation. This effect of high-molecular-weight chondroitin sulphate C decreased with increasing ionic strength. Heparin, though of low molecular weight (13000), was highly effective, as was also heparitin sulphate. The chondroitin sulphate-proteins of very high molecular weight were highly effective, despite the fact that for some preparations the component chondroitin sulphate chains had molecular weights much less than 20000. 3. Agents that had delayed fibril formation were also effective in producing an increase in degree of aggregation of fibrillar collagen, as indicated by dissymmetry changes observed in light-scattering experiments at low collagen concentrations. Methylated cellulose and heparin at 2.5mug./ml. were unusual in decreasing aggregation, but heparin at 0.25mug./ml. increased aggregation. Electron microscopy of gels showed fibrils and fibril aggregates with ;normal' collagen spacing and dimensions consistent with the light-scattering results. 4. The rates of electrical transport of agents and of solvent (electro-osmosis) through collagen gels indicated a contribution of molecular entanglement that increased with increase in molecular size of the agents. Electrostatic binding of heparin to collagen was noted. Binding to collagen during fibril formation was also found for heparitin sulphate and a chondroitin sulphate with extra sulphate groups. 5. Electrostatic binding of acid mucopolysaccharide-proteins to collagen may be an important factor in the organization and functioning of connective tissues at all stages of growth and development. Excluded-volume (molecular-entanglement) effects may also be important. These factors operate simultaneously and interact mutually so that precise assessment of their relative importance is difficult.

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The acid mucopolysaccharides of cattle retina.

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