Distribution of cathepsins in red and white muscles among fish species

We examined the distribution of several cathepsins (cathepsins B, B-like, L and D, and latent cathepsin L) in red and white muscles among 24 species o f marine and freshwater fish. All activities of cathepsins except cathepsin D of marine red-flesh fish were relatively higher than that of marine whit e-flesh fish and freshwater fish. The activity of cathepsin D was detected in red or white muscle of all fish, and no difference can be seen between f ish species.