Table I.

Significant atomic distances (Å) of different catalytic site residues of cysteine proteases with selected inhibitors at S₁ - P₁ site

E-64 & Protease	Papain Caricain		Chymo	Actinidin	Calotropin
	[19]	[21]	papain	[20]	DI
O5.....66(Gly):N	2.88	2.78	-	2.92	3.37
N10.....66(Gly):O	3.04	2.94	3.23	2.91	3.49
N6.....158(Asp):O		3.27	3.58	3.15	3.60
O18.....159(His):ND1	2.90	2.88	2.76	2.80	3.10
O17.....19(Gln):NE2	2.87	2.74	2.88	2.91	3.22
O17.....25(Cys):N	2.95	3.01	3.05	2.94	3.54
O17.....25(Cys):SG		3.36	3.33	3.24	2.81
E-64-C & Protease	Papain	Caricain	Chymo	Actinidin	Calotropin
	[33]		Papain		DI
O5...66(Gly):N	3.16	2.88	3.28	3.05	3.21
N10...66(Gly):O	3.46	-	3.30	3.64	-
O17...19(Gln):NE2	2.90	3.35	3.12	3.25	3.18
O17...25(Cys):N	2.75	3.20	3.11	2.36	2.84
O17...25(Cys):SG	2.61	3.35	3.01	3.08	2.79
O18...159(His):ND1	3.76	3.38	3.32	3.56	3.39
N6...158(Asp):O	2.99	3.17	3.27	3.43	3.40
Leupeptin & Protease	Papain	Caricain	Chymo	Actinidin	Calotropin
	[34]		Papain		DI
2 Leu:N...66(Gly):O	3.05	3.14	3.50	3.24	3.29
2 Leu:O...66(Gly):N	2.78	3.17	3.13	3.09	3.07
3 Arg:N...25(Cys):SG	3.01	3.06	3.26	3.22	3.02
3 Arg:N...158(Asp):O	3.03	2.69	3.09	2.80	2.93
3 Arg:O...19(Gln):NE2	2.88	3.17	3.21	3.17	3.18
3 Arg:O...25(Cys):SG	2.62	2.65	2.66	2.71	2.56
3 Arg:O...25(Cys):N	3.00	3.28	3.50	3.16	3.46
ZPACK & Protease	Papain	Caricain	Chymo	Actinidin	Calotropin
	[30]		papain		DI
N11...66(Gly):O	2.84	2.98	-	2.85	3.61
O8...66(Gly):N	2.96	3.10	3.29	3.10	2.85
O3...25(Cys):N	3.61	3.25	3.40	2.85	3.84
O3...25(Cys):SG	3.30	3.45	3.18	3.05	3.28
O3...19(Gln):NE2	3.56	3.36	3.60	3.36	3.20

Footnote: The numbers in square brackets are reference numbers In the table, the distances are typed as normal for the modeled complexes and x-ray crystallographic values are in italics. Residue numbers are according to papain sequence