. Author manuscript; available in PMC: 2014 Mar 30.

Published in final edited form as: Nat Rev Microbiol. 2013 Mar;11(3):205–212. doi: 10.1038/nrmicro2970

Table 2.

Bacterial oxidases that use O₂ as a terminal electron acceptor

	Low-affinity terminal oxidases	High-affinity terminal oxidases
Family	HCOs	HCOs	HCOs	Cytochrome bd-type oxidases
Class	A	C	B	No class divisions
Representatives	Cytochrome aa₃ oxidase and cytochrome bo₃ oxidase	Cytochrome cbb₃ oxidase	Cytochrome ba₃ oxidase	Cytochrome bd oxidase
Catalytic subunits^*	CtaD or CyoB	FixN (also known as CcoN in some species)	CbaA	CydA
K_m	200 nM (REF. 33)	7 nM (REF. 47)	NA	3–8 nM (REF. 34)
H⁺ pump	Yes	Yes	Yes	No

HCOs, haem–copper oxidases; K_m, Michaelis constant. NA, not available.

The catalytic subunits listed are those responsible for the transfer of electrons to O₂.