TABLE 1.

MPT/molybdenum and phosphorus/molybdenum ratios in different protein samples

Sample	MPTa/Molybdenumb	Phosphorus/Molybdenumc
MobA + Mo-MPT	2.18 ± 0.64	2.2 ± 0.7
MobA + Mo-MPT + Mg-GTP	2.28 ± 0.68	3.7 ± 0.8
MoeA + Mo-MPT	0.98 ± 0.06	NDd
hSO	1.02 ± 0.03	ND
TorA	ND	3.5 ± 0.6

^a MPT was detected after conversion to form A.

^b Molybdenum was quantified by inductively coupled plasma optical emission spectroscopy.

^c Phosphorus and molybdenum contents were determined by total reflection X-ray fluorescence analysis. The given ratio for MobA + Mo-MPT represents the average of measurements on five independent samples; two samples each for the other conditions were analyzed. The error gives the S.D. MobA + Mo-MPT samples contained 0.67 ± 0.20 mm protein, 0.44 ± 0.18 mm phosphorus, and 0.21 ± 0.09 mm molybdenum on average, consistent with ∼30% cofactor loading of MobA. TorA was used at a concentration of 0.42 mm.

^d ND, not determined.