Cathepsin H (EC 3.4.22.16)

Abstract In 1976 Kirschke and co-workers [169] named a lysosomal peptidase cathepsin H. This enzyme was termed L20C21 in 1972 by the same authors [340] and later cathepsin B3 [ 343], because of similarities to cathepsin B (then known as cathepsin B1). Histochemical demonstration by Sylven in 1968 [718] of a thiol-dependent lysosomal enzyme active against Leu-NHNap is now attributable to cathepsin H. In 1975 Davidson and Poole [1372] partially purified an enzyme hydrolysing Bz-Arg-NHNap, but different from cathepsin B, from rat liver lysosomes. This enzyme obviously was cathepsin H. A BANA hydrolase from rat skin described by Jarvinen and Hopsu-Havu in 1975 [1385] was identified in 1985 by immunological methods as cathepsin H [1009]. A benz!ijlarginine-/3-naphthylamide hydrolase isolated from rabbit lung by Singh and Kalnitsky in 1978 [392] was reported to degrade collagen [264] and in 1983 was named cathepsin I by Kalnitsky et al. [1261]. However, in later work by Kirschke and co-workers in 1986 [171], preparations of this enzyme from rabbit lung and rat lung did not show collagenolytic activity, but showed high cross-reactivity with an antibody to cathepsin H from rat liver. There was therefore no reason to retain the name cathepsin I for the enzyme from rabbit lung. The name cathepsin H (EC 3.4.22.16) was recommended by the nomenclature committee of IUB in 1981.