Lysosomal enzyme activities of the bovine corneal endothelium.

A quantitative study was carried out on the lysosomal enzyme activities of the bovine corneal endothelium-Descemet's membrane preparation. The corneal endothelium and Descemet's membrane were peeled off together. Cathepsin D was assayed using hemoglobin as substrate; N-acetyl-beta-D-glucosaminidase, beta-glucuronidase, acid phosphatase, and alpha-mannosidase were also examined using p-nitrophenyl derivatives as substrate. The proportions of N-acetyl-beta-D-glucosaminidase, cathepsin D, and beta-glucuronidase of the Descemet's membrane-endothelium complex were particularly high: 11.5%, 12.6%, and 12.5% of the whole cornea, respectively. Corneal endothelial cells also showed high activities of acid phosphatase and alpha-mannosidase (3.8%, and 5.0% of the whole cornea, respectively), while the protein and DNA contents were 0.5% and 0.5% in the complex. Lysosomal enzyme activities in the complex were also compared with those in other ocular tissues and were determined by the same methods at the same time.