Cathepsins D from sea urchin egg Tetrapygus niger—Isolation by affinity chromatography and properties

Abstract

1. 1. Cathepsins D-I and D-II, were partially purified and characterized from unfertilized sea urchin egg Tetrapygus niger. 2. 2. The purification was achieved by ammonium sulfate precipitation, gel filtration on Sephadex G-200 and affinity chromatography on hemoglobin agarose. 3. 3. Cathepsin D-I showed the maximal activity on denatured urea hemoglobin at pH 3.9 while cathepsin D-II showed maximal activity at pH 3. 4. 4. Cathepsin D-I presented a molecular weight of 52,000 and cathepsin D-II a molecular weight of 35,000 both determined by Sephadex G-100 chromatography. 5. 5. On polyacrylamide disc-gel electrophoresis cathepsin D-I showed two bands with proteolytic activity, different molecular weights and mobilities. Cathepsin D-II showed only one band with proteolytic activity and higher electrophoretic mobility than D-I.