id	author	title	date	pages	extension	mime	words	sentences	flesch	summary	cache	txt
cord-006934-92ctgc4n	Barrett, Alan J.	Families and clans of cysteine peptidases	1996		.txt	text/plain	3364	168	54	In all the cysteine peptidases discovered so far, the activity depends upon a catalytic dyad, the second member of which is a histidine residue acting as a general base. The amino acid sequences of the cysteine peptidases of picornaviruses (picornains 2A and 3C) (family C3) hint at a relationship with chymotrypsin [34] , and when the threedimensional structure of picornain 3C from the human hepatitis A virus was determined, it showed unmistakable similarities to that of chymotrypsin and other members of clan SA [6, 35] . There are additionally many polyprotein processing endopeptidases from RNA viruses that have the Cys/His catalytic dyad, and also show the bulky hydrophobic amino acid following the catalytic cysteine that is characteristic of the papain clan. The three-dimensional structure of interleukin-l[3-converting enzyme shows a distinctive protein fold, and thus a separate origin for this group of cysteine peptidases [7, 8] .	./cache/cord-006934-92ctgc4n.txt	./txt/cord-006934-92ctgc4n.txt