Table 1.

Kinetic parameters for translocation of RecQ on ssDNA

Kinetic Parameter	Definition	Units	Dissociation Data	Pi Release Data
kt	Forward stepping rate	steps/s	3.0 ± 0.6	-
kend	Dissociation rate from DNA end	s-1	6 ± 1	-
r	Ratio of binding DNA internally vs. end	-	7.1 ± 0.7	-
m	Kinetic step size	nt/step	5.3 ± 0.9	-
kd	Dissociation rate (0.5 mg/mL heparin)	s-1	0.75 ± 0.01	-
kd	Dissociation rate (no heparin)	s-1	0.43 ± 0.04	-
m•kt	Translocation rate	nt/s	16 ± 4	14.0 ± 0.4
d	Binding site size	nt	34 ± 3	34 ± 0.7
c	Coupling efficiency per step	ADP/step	-	3.4 ± 0.4
c/m	Coupling efficiency per nucleotide	ADP/nt	-	0.6 ± 0.2
m/c	Nucleotides translocated per ATP hydrolyzed	nt/ATP	-	1.6 ± 0.3
P	Processivity (0.5 mg/mL heparin)	-	0.952 ± 0.005
P	Processivity (no heparin)	-	0.972 ± 0.002	-
Nav = 1/(1-P)	Average distance (0.5 mg/mL heparin)	nt	21 ± 2	-
Nav = 1/(1-P)	Average distance (no heparin)	nt	36 ± 2	-

The parameters k_t, k_end, and r were determined by fitting the data in Fig. 4A to Eq. 6. The values are reported as an average of the three datasets with standard deviation. The dissociation rate constant from internal ssDNA sites was determined from experiment with poly dT using Eq. 4 (Fig. S5). The values for the binding site size, d, and kinetic step size, m, were determined from linear least squares fitting to the data in Fig. 4B. The coupling efficiency, c, and site size, d, in the “P_i release” data column were determined from the fit of Eq. 8 to the amplitudes of the phosphate-release data in Fig. 2B.