... proteinaceoussubstrate at neutral pH. Moreover, this conformationalchange, which is the only unimolecular step of themechanism, is not accompanied by any larger struc-tural changes, such as unfolding ... A, Lang A, Horler D, Kissling R & Merlin C(1995) Cathepsin B in osteoarthritis: cytochemical andhistochemical analysis of human femoral head cartilage.Ann Rheum Dis 54 , 289–297.7 Coulombe ... ofprocathepsin B is largely unaffected by mutations in this region, includingmutations to prolines. On the basis of these results, a model for autocata-lytic activation of cysteine cathepsins is proposed,...