TABLE 1.

Purification of acetone carboxylase from R. capsulatus B10

Step	Volume (ml)	Total protein (mg)	Total activity (U)a	Sp act (U/mg)	Purifi- cation (fold)	Recovery (%)
Cell extract	224	2,464	100.3	0.041	1.0	100
DEAE-Sepharose	367	488	59.9	0.123	3.0	60
Sephacryl S-300	98	226	51.8	0.230	5.6	52
Hydroxyapatite	10	152	36.4	0.240	5.9	36

^aActivity assays were performed using a mixture consisting of 0.1 to 0.4 mg of protein, 2 mM MgATP, 40 mM CO₂ plus KHCO₃, 3 mM acetone, 8 mM MgCl₂, and 40 mM potassium acetate and with an ATP-regenerating system consisting of 7 mM phosphoenolpyruvate, 6 U of pyruvate kinase, and 10 U of adenylate kinase. One unit of activity is defined as 1 μmol of acetone degraded per min at 30°C.