TABLE 2.

Conservation of key amino acids in α subunits of NDOs^a

Rieske center		Active site		Putative ferredoxin binding region		Electron transfer (Rieske active site)		Region of unknown function
NahAc	NarAa	NahAc	NarAa	NahAc	NarAa	NahAc	NarAa	NahAc	NarAa
C81	C88	N201	N209	K97	S104	W106	W113	T299	T297
C101	C108	H208	H216	G98	H105	V117	V124	V300	V298
H83	H90	H213	H221	V100	R107	R84	R91	F301	F299
H104	H111	D205b	D213	Q115	V122	E200	D208	P302	P300
		D362	D372	S116	G123			N303	N301
				P118c	P125c
				W211	M219

^aBoldface type indicates conservation of key amino acids. 

^bAsp205 is probably important for electron transfer (12) and is essential for activity (18). 

^cPro118 (as well as Trp211) is from the catalytic domain.