TABLE 2.

Summary of characteristics of heme binding to the best-characterized HmuY family members

HmuY family protein	Species	Heme iron coordinating ligandsa	Heme dissociation constant (Kd; M)		References
			Aerobic conditions	Reducing conditions
HmuY	P. gingivalis	His134, His166	<10−9	1.1 ± 0.2 × 10−8	(107, 109, 178)
Tfo	T. forsythia	Met143, Met169	4.9 ± 0.8 × 10−6	8.2 ± 2.7 × 10−9	(109, 112)
PinO	P. intermedia	Met150, Met176/Met76	9.2 ± 3.2 × 10−8	3.4 ± 1.6 × 10−9	(110)
PinA	P. intermedia	Met162, Met191	5.7 ± 0.3 × 10−6	2.0 ± 0.5 × 10−8	(110)
Bvu	B. vulgatus	Met145, Met172	ND	1.6 ± 0.6 × 10−9	(112)
BfrA	B. fragilis	Met146, Met175	1.8 ± 1.4 × 10−7	6.4 ± 0.8 × 10−8	(111)
BfrB	B. fragilis	None	1.4 ± 0.3 × 10−8	ND	(111)
BfrC	B. fragilis	None	ND	ND	(111)

^a Numbering in the full-length proteins is applied. ND, K_d not determined.