Table 2. Pre-steady state kinetic parameters of T4 Dam MTase interaction with duplexes containing a native or modified recognition site at limiting enzyme concentration^a.

Oligonucleotide substrate	Combination of duplexes	Recognition sequenceb	Burstc	kmeth (s–1)c	kcat (s–1)c
Canonical sites
		-G-A-T-C-	0.92	0.56	0.023
1	I + II	-C-T-A-G-	(0.05)	(0.10)	(0.002)
		-G-M-T-C-	0.85	0.47	0.021
1m	Im + II	-C-T-A-G-	(0.05)	(0.09)	(0.002)
		-G-M-T-C-	0.84	0.14	0.021
1md	Im + II	-C-T-A-G-	(0.07)	(0.04)	(0.002)
Substituted sites
		-G-A-T-C-	0.86	0.49	0.0051
2	I + III	-C-A-T-G-	(0.05)	(0.09)	(0.0005)
		-G-A-T-C-	0.90	0.67	0.0038
3	I + IIn	-C-T-N-G-	(0.03)	(0.12)	(0.0005)

^aEnzyme was preincubated with [³H-CH₃]-AdoMet prior to the addition of duplex.

^bN is 2-aminopurine; M is N⁶-methyladenine.

^cValues in parentheses correspond to standard deviations.

^dEnzyme was preincubated with duplex 1m before the addition of the [³H-CH₃]-AdoMet.