Table 2.

Dependence of ATP utilization by CYT-19 on Mg²⁺ concentration and duplex length

[Mg2+], mM	Duplex length
	6 bp	7 bp	9 bp	11 bp
2	0.45 ± 0.04	0.4 ± 0.1	1.1 ± 0.1	1.2 ± 0.1
5	0.90 ± 0.09	1.3 ± 0.4	1.4 ± 0.4	4.4 ± 0.7
10	1.1 ± 0.1	1.3 ± 0.2	5 ± 2	11 ± 2
20	2.0 ± 0.4	2.0 ± 0.4	14 ± 2	18 ± 2

Values are ATP hydrolyzed per duplex separated (ATP utilization value). Longer duplexes were derived from that shown in Fig 1A by extending the 5́-end of the RNA/DNA strand with uridine nucleotides. All reactions were performed at 25°C with 50 mM Na-MOPS (pH 7.0), 50 μM ATP-Mg²⁺, 0.5 μM duplex, and 2 μM CYT-19.