Table 3. Heme vibrational markers and vibrational modes and nitric oxide binding.

Protein	Coordination No.	Spin†	ν2 ‡	ν3	ν4	ν10	ν(Fe-NO)	Reference
Unligated
HcpR	6	ls	1586	1492	1362	1625		This work
sGC	5	hs	1562	1471	1358	1606		Deinum et al. (1996 ▸)
CooA	6	ls	1580	1492	1361	1616		Vogel, Spiro et al. (1999 ▸)
NO bound
HcpR	5	hs	1584	1508	1376	1646	535	This work
sGC	5	hs	1584	1509	1375	1646	525	Deinum et al. (1996 ▸)
CooA	5	hs	1582	1506	1376	1641	523	Reynolds et al. (2000 ▸)

^†ls, low spin; hs, high spin.

^‡All values are given in cm⁻¹.