Glycosidase activities in hog serum, optic nerve, and ocular tissues
Using spectrophotometric assay, we have studied the distribution of α-D-mannosidase, β-D-galactosidase, and N-acetyl-β-D-glucosaminidase in hog serum, the aqueous humor, optic nerve, retina, and uvea (iris, ciliary body, choroid). N-acetyl-β-D-glucosaminidase was the most active gycosidase in all tissues that we studied. The highest activity of α-D-mannosidase was found in the extracts prepared from the iris, while β-D-galactosidase and N-acetyl-β-D-glucosaminidase were the most active in the extracts of the choroid and ciliary body, respectively. The aqueous humor and serum had several times lower specific activity of glycosidases than did the extracts of ocular tissues or optic nerve. There was no significant difference between the activity of these enzymes in the aqueous humor and serum. High activity of glycosidases in the optic nerve suggests their role for intrinsic axonal repair. Retinal extracts had the smallest glycosidase activity of all ocular extracts prepared. The physiological role of these findings is discussed.