Enzymic sulfation of corneal mucopolysaccharides by beef cornea epithelial extract.

On an anatomical basis, cornea may be divided into three major parts: the fibrous stroma, the overlying epithelium, and endothelium. Epithelial and endothelial cells contribute approximately 20% of the total wet weight of beef cornea, and their integrity is essential for stromal maintenance (1). Of the three major parts of cornea, epithelial cells have the highest oxygen consumption that can be compared with that of liver (1). In agreement with the high oxygen consumption, the quantitation of glycolytic enzymes in cornea has shown higher activities in the epithelium than in the stroma (2, 3). A recent study has shown that all parts of beef cornea contain phenol sulfotransferase, which is also more active in the epithelium than in the stroma (4). Gregory and Lipmann (5) suggested that phenol sulfotransferase might be coupled with other sulfotransferases so that it would act as a feeder system which could be assayed spectrophotometrically. When phenol and steroid sulfotransferases were tested as a coupled enzyme system, no transfer of sulfate to a steroid acceptor was detected because of an inhibitory effect of 3’-phosphoadenosine 5’-phosphate. Nevertheless, this mechanism cannot be eliminated as a feasible assay procedure. Its successful use would facilitate the characterization of sulfotransferases. The present communication demonstrates the presence of phenol and mucopolysaccharide sulfotransferase activities in beef cornea epithelial extract. Furthermore, it reopens the possibility of using phenol sulfotransferase as a feeder system for the assay and characterization of mucopolysaccharide sulfotransferase.