The presence of collagenolytic cathepsin in uveal lysosomes of bovine eye.

Collagenolytic cathepsin, which can liberate soluble hydroxyproline-containing products from insoluble vitreous collagen with maximum activity at pH 3.5, was biochemically studied in uveal lysosomes of bovine eye. Collagen solubilization was proportional to both enzyme concentration and incubation time. When the enzyme was heated, no reaction was observed. Collagen solubilization by uveal lysosomal extract was almost unaffected by Ca2+ ion, cysteine, beta-mercaptoethanol, and ethylenediaminetetraacetic acid, but inhibited about one-third by pepstatin. The possible role of collagenolytic cathepsin in vitreous liquefaction was considered.