Table 1.

MEROPS Serine Protease Clans

MEROPS Clan	Family Number	Structure Example	SCOP Class	SCOP Fold	Catalytic Motif
SB	2	1scn	α/β	Subtilisin-like	D-H-S
SC	6	1qtr	α/β	α/β hydrolase	S-H-D
SE	3	1es4	multi	β-lactamase-like	SxxK
SF	2	1umu	all-β	LexA/Signal peptidase	S-K
SH	5	1lay	all-β	Herpes virus serine proteinase, assemblin	H-S-H
SJ	3	1rr9	α+β	Ribosomal protein S5 domain 2-like	S-K
SK	3	1tyf	α/β	ClpP/crotonase	variable
SO	1	3gw6	na	na	S-K
SP	1	1ko6	all-β	C-terminal autoproteolytic domain of nucleoporin nup98	HxS
SR	1	1lct	α/β	Periplasmic binding protein-like II	K-S
SS	1	1zrs	α/β	Flavodoxin-like; “swivelling” β/β/α domain	S-E-H
ST	1	2ic8	membrane	rhomboid-like	S-H
PA	14	1bra	all-β	Trypsin-like	H-D-S
PB	2	1pnk	α+β	Ntn hydrolase-like	S
PC	1	1fye	α/β	Flavodoxin-like	S-H-E