Table 1.

Active site parameters of convergently related Ser proteases

Clan	Enzyme	PDB	Complex	Reactive rotamer	ϕ, ψ angles	Catalytic motif	Oxyanion hole	Face of attack	χcat	αcat	χoxy	Reference
PA	Elastase	3HGN	Hemiketal	g−	(−43, 140)	S-H-D	N	re	−131	125	−32	(68)
SB	Sedolisin	1GA4	Ester	g−	(−62, −24)	S-E-D	N	re	−147	108	−18	(69)
SE	D-Ala-D-Ala peptidase	1MPL	Phophonate	g−	(−72, 0)	S-Y-K	N	re	−156	97	−48	(70)
SC	Prolyl aminopeptidase	1QFM	Hemiketal	t	(66, −115)	S-H-D	N + 1	si	117	106	32	(26)
SS	L,D-carboxypeptidase	1ZRS		t	(64, −130)	S-H-E	N + 1	si	109			(49)
PC	Aspartyl dipeptidase	1FYE		t	(57, −122)	S-H-E	N + 1	si	84			(71)
SH	CMV protease	1NKM	α-Ketoamide	t	(−177, 132)	S-H-H	Extrinsic	re	−125	111	−39	(23)
SK	ClpP	1FZS	HMK	t	(59, −122)	S-H-D	N + 1	si	130	74	50	(29)
SF	Signal peptidase	1B12	Ester	g+	(−68, −11)	S-K	N	si	148	109	1	(60)
SJ	VP4 protease	3R0B	Ester	g+	(−65, −13)	S-K	N	si	173	114	−9	(72)
ST	Rhomboid-1	2IC8		g+	(−63, −29)	S-H	N	si	113			(73)

Halomethyl ketone (HMK) inactivators give rise to unusually small α_cat values. See text for details.