Metabolism of sulfate by beef and rabbit cornea

Abstract

Beef and rabbit corneal stromas will incorporate inorganic sulfate-S³⁵ in vitro. Species differences with respect to the influence of epithelium on this uptake and the distribution of phenol sulfokinase and of arylsulfatase in various parts of cornea have been observed. Rabbit stroma is dependent upon an intact epithelium for its uptake but de-epithelialization is without effect upon the uptake of inorganic sulfate-S³⁵ into beef stroma. Beef cornea epithelial, stromal and endothelial extracts were found to contain phenol sulfokinase and no detectable arylsulfatase activity. The latter enzyme was found in rabbit cornea stromal extract but not in epithelial-endothelial extract. Arylsulfatase has been partially characterized. Nitrocatechol sulfate and p-nitrophenyl sulfate were hydrolyzed at the rate of 280 and 30 mµmoles/hr/mg of extract protein at their pH optima 5.5 and 7.4 at 38°, respectively. The effect of various known arylsulfatase inhibitors was observed, and the results suggested two arylsulfatases. Efforts to find two separate arylsulfatase activities after electrophoresis of rabbit corneal extract on starch were inconclusive.