Abstract
On sequential extraction of bovine corneas with 0.155 M NaCl and 1 M CaCl2 two macromolecular fractions were obtained in a ratio of 0.7–1.5, both containing glycosa-minoglycans and a hexosamine containing non-glycosaminoglycan subfraction.
Electron microscopy revealed that the NaCl extraction has no effect on the form, the diameter, the course of the collagen fibrils or their distance from each other. Unlike previous studies, CaCl2 extraction leads to only minimal disruption of lamellar organization or collagen fibrils. This incomplete extraction is probably attributable to the presence of an intact epithelium which is necessary for the incorporation experiments below.
Incubation of bovine cornea in the presence of 1- 14C glucosamine results in a specific labeling of all hexosamine-containing compounds. The chondroitin sulfate preparations isolated from the saline and CaCl2 extracts had equal specific radioactivity. However, the specific radioactivities of the keratan sulfates isolated from the NaCl extract was 3–5 times higher than that of the keratan sulfate prepared from the CaCl2 extract.
In a pulse-chase experiment no shift in the ratio of the specific radioactivities of the two keratan sulfate preparations was observed. From these results it is concluded that two metabolically independent keratan sulfate fractions in two topographically different sites may be present in the stroma. The less labeled keratan sulfate and its proteoglycan, respectively, are thought to be involved in the maintenance of corneal collagen structure.
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© 1979 Dr W. Junk b.v. Publishers
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Dische, Z., Cremer-Bartels, G., Kaye, G.I., Kaye, N.W., Buddeke, E. (1979). Metabolic Heterogeneity of Keratan Sulfate in Bovine Cornea and its Role in the Maintenance of Corneal Collagen Structure. In: Hockwin, O., Rathbun, W.B. (eds) Progress in Anterior Eye Segment Research and Practice. Documenta Ophthalmologica Proceedings Series, vol 18. Springer, Dordrecht. https://doi.org/10.1007/978-94-009-9609-0_29
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DOI: https://doi.org/10.1007/978-94-009-9609-0_29
Publisher Name: Springer, Dordrecht
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