Table 1.

Summary of mass spectrometric data

Sample description	No. of samples	Relative enrichment, δ18O, ‰	Standard deviation, ‰
Controls
Buffer*	8	22.00	1.10
Buffer + 18O2	2	20.89	0.06
Buffer + CN	2	20.69	0.53
oxCcO	4	22.85	0.40
oxCcO + 18O2	2	22.70	0.25
oxCcO.CN + 18O2	2	22.67	0.57
oxCcO + 300 μM H218O	2	26.63	0.06
Calibrations
Buffer + 150 μM H218O	6	23.48	1.88
Buffer + 300 μM H218O	10	26.52	1.09
Buffer + 600 μM H218O	6	28.94	0.45
Compound P (228 μM)	3	24.59	0.89

^*The buffer was composed of 55 mM Tris-SO₄ (pH 8.0) containing 0.1% n-dodecyl-β-d-maltoside. (CN, cyanide; oxCcO, oxidized CcO; oxCcO.CN, oxCcO complexed with CN.