Distribution of lysosomal hydrolases in human and bovine ocular tissues

Abstract

We have studied the distribution of the lysosoma1 sphingolipid hydrolases β-glucosaminidase, β-galactosaminidase, β-galactosidase, α- and β-glucosidases, and α-mannosidase in the bovine and human ocular tissues, choroid, cornea, lens, retina, and sclera using synthetic substrates in the form of the 4-methylumbelliferyl derivatives of the corresponding glycosides. As compared to the bovine ocular tissues, the human ocular tissues possessed higher levels of all the enzyme activities examined with the exception of β-glucosidase in the cornea. Bovine retina contained higher levels of fi-hexosaminidases, β-galactosidase, and a-glucosidase than the other bovine ocular tissues. In contrast to the retina, which is primarily a neural tissue, human and bovine lens have minimal or trace levels of all the lysosomal hydrolases examined. Human and bovine retina, cornea, sclera, and choroid possess enzyme activities which are higher than the lens. This would indicate a slow turnover of glycosphingolipids in lens tissue as compared to the other ocular tissues.