Are there species differences amongst the lysosomal cysteine proteinases?

Kinetic constants for the hydrolysis of synthetic substrates by cathepsin B, cathepsin L or cathepsin H show only small variations between various species. The species variants purified from human, beef and rabbit reacted with antisera raised against the enzymes from rat. With regard to these criteria we could show that cathepsin I from rabbit lung is a species variant of cathepsin H, whereas cathepsin S is a separate enzyme from cathepsin L.