Vitamin A deficiency and the glycoproteins of rat corneal epithelium
Kim, Y.C.; Wolf, G.
Journal of Nutrition 104(6): 710-718
1974
ISSN/ISBN: 0022-3166 PMID: 4830275 Document Number: 77197
Weanling male Holtzman rats were fed on vitamin A-deficient diet; normal controls were pair-fed on the deficient diet and given 30 mu g retinyl acetate daily. Vitamin A solution was added to the deficient diet every fourth day for the pair-fed control rats. After 5 to 6 weeks whole corneas from both groups were incubated with radioactive precursors of glycoproteins; glycoproteins from separated endothelial tissue were then extracted and treated enzymically to yield glycopeptides. Glycopeptides eluted between 0.35 and 0.42 N LiCl in a continuous gradient from a DEAE-Sephadex column were significantly affected by vitamin A deficiency. These affected glycopeptides were further separated by polyacrylamide gel electrophoresis and, when their carbohydrate content was investigated by gas-liquid chromatography, it was shown that they did not contain fucose and the molar ratio of sialic acid to hexosamine, 1.5 to 1.9, was much higher than that, 0.3, of a similar vitamin A-sensitive glycopeptide isolated from rat small intestinal mucosa by De Luca et al. (Journal of Biological Chemistry (1970) 245, 4551).