Table 4. Catalytic sequence motifs in type II restriction endonucleases.

Enzyme	PD motif	D/EXK motif	Reference
EcoRI	PD91	E111AK	189
EcoRV	PD74	D90IK	47
BamHI	ID74	E111FE	100
PvuII	ND58	E68LK	43,48
Crf10Ia	PD134	(E204) S188VK	190,191
FokI	PD450	D467TK	53
BglI	PD116	D142IK	49
MunI	PD83	E98IK	98
NaeI	TD86	D95CK	42
BglII	ID84	E93VQ	99
NgoMIVa	PD140	(E201) S185CK	45
BsoBI	VD212	E240LK	52

^aThe crystal structure analysis has shown that the second acidic residue of the PD . . . D/EXK motif is recruited for the catalytic center from a distal part of the structure.