Acidic lens protein degrading activity in bovine ciliary body

Biochemical studies of acidic lens protein degrading activity in the bovine ciliary body were performed. The activity showed two peaks, Fractions A and B, on Sephadex G-75 column chromatography. Fraction A contained cathepsin D and thiol proteinase activities and was inhibited by pepstatin and leupeptin. Fraction B contained thiol proteinase activity and was inhibited by leupeptin. The proportion of peptide released from the lens protein by Fractions A and B was higher than those from bovine serum albumin and casein. Lens protein may be a good assay substrate for cathepsin D and lysosomal thiol proteinase in the ciliary body.