Important for the overall degradation of proteins in lysosomes. Hydrolysis of proteins, acting as an aminopeptidase (notably, cleaving Arg-|-Xaa bonds) as well as an endopeptidase. Composed of cathepsin H and mini chain; disulfide-linked. Cathepsin H may be split into heavy and light chain. All chains are held together by disulfide bonds. Belongs to the peptidase C1 family.