Table 1.

Molecular weights and structural conformations determined by analytical ultracentrifugation of wild-type, R548K, R548Q, R548A, Q552N and Q552A RePC^a

Enzyme form	Monomerb Sedimentation Coefficient	Molecular mass (kDa)	%	Dimerb Sedimentation coefficient	Molecular mass (kDa)	%	Tetramerb Sedimentation cofficient	Molecular mass (kDa)	%
wild-type		14% of monomers and dimersc					17.1 ± 1.2	472 ± 52	86
R548K	8.2 ± 0.8	183 ± 27	13	10.8 ± 1.0	289 ± 37	13	17.7 ± 1.2	591 ± 69	74
R548Q	7.7 ± 0.6	143 ± 17	9	10.6 ± 1.7	239 ± 55	42	18.5 ± 1.2	518 ± 52	49
R548A	5.8 ± 0.9	99 ± 24	13	10.1 ± 1.1	218 ± 43	53	16.8 ± 1.1	451 ± 44	34
Q552N	7.8 ± 0.6	172 ± 19	11	10.4 ± 0.9	267 ± 37	13	17.4 ± 1.0	575 ± 57	76
Q552A	6.8 ± 0.7	123 ± 21	15	9.7 ± 1.1	203 ± 34	12	16.9 ± 1.9	471 ± 75	73

^aAnalytical ultracentrifugations were performed at 30°C in 0.1 Tris-HCl pH 7.8, 20 mM NaHCO₃, 5 mM MgCl₂, 10 mM pyruvate, 0.1 mM acetyl-CoA, 1 mM DTE using 0.2 mg/ml enzyme.

^bListed under these headings are enzyme species that have sedimentation coefficients that are most appropriate to the particular quaternary conformation in the context of the enzyme sample analysed. The subunit molecular mass is theoretically 126,009 Da.

^cUnable to obtain separate estimates of dimers and monomers.