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ZACHARIAS DISCHE, GINEVRA ZELMENIS; Glycoproteins of the Lens in Relation to Age and Cataract Formation II. Glycoproteins of lens fibers of rabbit. Invest. Ophthalmol. Vis. Sci. 1963;2(1):90-97. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
The encapsulated lens fibers of rabbit contain glycoprotein fractions with the carbohydrate moiety consisting of galactose, mannose, glucosamine, fucose, and derivatives of neuraminic acid. Most of this glycoprotein fraction is spun down in 30 minutes at 600 x G with the main bulk of the albuminoid. One part sediments only at 10,000 x G in 60 minutes. The total amount of this carbohydrate is significantly higher in the cortical part than in the nuclear part of the lens in 4-week-old rabbits as well as in animals of more than 1 year of age. The concentration of the carbohydrate per unit wet weight increases between the age of 3 months and 1 year by about 50 per cent in the 600 x G fraction and very much more in the cortical fraction sedimenting at 10,000 x G. The composition of the carbohydrate in the nucleus differs from that in the cortex by a lower ratio of sialic acid to fucose and a higher proportion of galactose among hexose constituents. A continuous decrease in the ratio of sialic acid to fucose also takes place in the cortical and nuclear parts during the aging of the animal. The proportion of the glucosaminoglycan extracted by alkaline ethanol at room temperature shows a lower ratio of sialic acid to fucose than the total protein-bound carbohydrate extracted by a 10 per cent solution of trichloroacetic acid at 90° C. The possible biologic significance of the glycoprotein fraction of the lens fibers is discussed.
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