Table 1.

Purification of dMTase from A549 cells

Purification step	Total protein, μg	Specific activity, pmol/hour/μg	Fold purification
Nuclear extract	6,000	1.83  × 10−5	—
DEAE-Sephadex	3.75	0.156	844.5
SP-Sepharose	0.77	0.663	35,939.84
Q-Sepharose	0.46	1.13	62,860
DEAE-Sephacel	0.018	10.19	552,243

Nuclear extract from A549 cells (1 ml, 6 mg) was applied sequentially onto a DEAE-Sephadex, SP-Sepharose, Q-Sepharose, and DEAE-Sephacel columns as described in Materials and Methods. dMTase was assayed by using a 50-μl sample of each 0.5-ml fraction using the assay described in Fig. 1 and Ref. 11. The specific activity of the active fractions after each purification step is represented as picomoles of CH₃ released per hour per microgram of protein. The ratio of specific activity of dMTase after each step to that of the nuclear extract is shown as fold purification.