Cathepsin D and an alkaline protease activities in subretinal fluid.

It was found that subretinal fluid contains at least two different proteolytic enzymes which digest various protein substrates. The main of them was identified as cathepsin D. This protease is very active towards the denatured haemoglobin. The highest activity is apparent at pH 3-4 and it is completely inhibited by the action of pepstatin. The cathepsin activity increases with the duration of retinal detachment. The other proteolytic enzyme acts at slightly alkaline pH. Its activity is lower and does not change with the duration of the disease.