Assay procedures for cathepsin B, H and L activities in rat tissue homogenates

Cathepsin B, H and L activities in small amounts of rat tissue homogenates corresponding to 10 micrograms protein were determined with 7-amino-4-methyl-coumarin conjugates as substrates. A new procedure for serum cathepsin H activity was also developed. High cathepsin B and H activities were found in kidney, spleen and liver. Liver cathepsin B, H and L activities in D-galactosamine-injured rats were decreased concomitantly with an increase in serum cathepsin H activity.