TABLE 2.

Enzymatic activities of type II DNA topoisomerases

Strain source of subunit for purification				Enzyme sp acta
				Gyrase		Topo IV
ParC	ParE	GyrA	GyrB	Supercoilingb	Cleavagec	Decatenationd	Relaxatione	Cleavagef
-	-	R6	R6	8.6	3.7	-	-	-
-	-	T14	R6	4.3 (2.0)	1.0 (3.7)	-	-	-
R6	R6	-	-	-	-	21.2	1.4	3.8
T1	R6	-	-	-	-	10.6 (2.0)	0.9 (1.5)	1.2 (3.2)
T14	R6	-	-	-	-	6.5 (3.3)	0.9 (1.5)	1.4 (2.7)
T14	T14	-	-	-	-	8.3 (2.5)	0.7 (2.0)	1.1 (3.4)

^aActivities are in units/mg × 10⁴, and numbers in parentheses are the fold decrease in activity with respect to that of the R6 enzyme.

^bOne unit defined as the amount of enzyme required to convert 50% of 0.4 μg of relaxed pBR322 to the supercoiled form in 1 h at 37°C.

^cOne unit defined as the amount of enzyme required to linearize 20% of 0.4 μg of CCC pBR322 in 30 min at 37°C.

^dOne unit defined as the amount of enzyme required to decatenate 50% of 0.4 μg of kDNA in 1 h at 37°C.

^eOne unit defined as the amount of enzyme required to convert 50% of 50 ng of CCC pBR322 to the open circle form in 1 h at 37°C.

^fOne unit defined as the amount of enzyme required to linearize 50% of 0.4 μg of CCC pBR322 in 30 min at 37°C.