Figure 1. Plasminogen and angiostatins in corneal extracts

Three human corneas from different donors were separated into layers of epithelial (Epi), endothelial (End), and stromal (Str) material, and then each layer was homogenized in a Tris buffer in the presence of a mixture of proteinase inhibitors. Extracts of equal total protein concentrations were diluted in SDS-loading buffer and separated on nonreducing 10% SDS-PAGE, transferred to nitrocellulose and probed with two antibodies specific for the K1-3 portion of the plasminogen molecule. The epithelial, stromal and endothelial layer extracts contained plasminogen (Plgn) and K1-4 and K1-3 angiostatin-like molecules. The relative amounts of the products depended upon the corneal layer and the specific donor.