TABLE 1.

Pathways model estimates for the electron transfer reaction from Cu_A to heme a in the crystallographic and equilibrium conformations

Ligand	No. of steps	kET, s−1 (cryst.)	kET, s−1 (equil.)
CysB196	24 + 2 + 0	3 × 102	2 × 102
GluB198	16 + 1 + 1	1 × 105	5 × 101
CysB200	18 + 1 + 1	2 × 104	7 × 10°
HisB204	14 + 2 + 0	9 × 105	5 × 106

The second column shows the numbers of covalent steps, hydrogen bond steps, and through-space jumps in each pathway. The steps are counted from Cu_A to Fe of heme a.