TABLE 2.

Comparison of nuclear quadrupole tensors and hyperfine couplings for ¹⁴N histidine nitrogens involved in hydrogen bond formation with the semiquinone in different quinone-processing sites

Semiquinone site	|K|	η	A	Ref.
Qi in bc1 complex	0.36	0.17	0.75	This work
QA in PS II (Nδ)	0.35	0.69	1.7	66
QA in PS II (Nδ)	0.39	0.69	1.9	67
QB− in R. sphaeroides (Nδ)	0.41	0.61		68
QA− in R. sphaeroides (Nδ)	0.41	0.73		68,69
QA− in Rhodopseudomonas viridis (Nδ)	0.41	0.69		68
QA− in R. sphaeroides (Nδ)	0.38	0.82	1.8	59
QH in D75H mutant of E. coli cytochrome bo3 oxidase	0.43	0.73	2.7	60
N∊ in L-histidine monochloride	0.366	0.268		41
Nδ in L-histidine monochloride	0.32	0.946		41