Table 1.

Comparison of K_m and k_cat among PfuHAN and its truncated proteins

	ssDNA			ssRNA
	K m (μM)	k cat (min−1)	k cat/Km (min−1·μM−1)	K m (μM)	k cat (min−1)	k cat/Km (min−1·μM−1)
HAN	3.6±0.2	0.096±0.01	0.027±0.003	2.7±0.2	0.064±0.005	0.024±0.002
D1	58.4±0.6	0.056±0.004	0.001±0.0001	46.4±0.4	0.034±0.004	0.0007±0.00005
D2	43.3±0.5	0.065±0.004	0.0015±0.0001	29.9±0.3	0.048±0.003	0.010±0.0004
D3	41.4±0.3	0.070±0.006	0.0017±0.0001	25.2±0.3	0.052±0.004	0.0016±0.0002
D4	14.1±0.3	0.084±0.007	0.0060±0.0001	10.4±0.3	0.058±0.004	0.0056±0.0005
D5	8.8±0.3	0.086±0.008	0.010±0.001	6.1±0.2	0.062±0.005	0.010±0.001

K _m and k_cat were calculated by double reciprocal plotting using the initial reaction rates at various substrate concentrations (0.05, 0.1, 0.25, 0.5, 1.0 and 2.0 μM). The kinetic parameters were determined in the presence of 15 nM PfuHAN and each truncated protein. The substrates are 3′-FAM-labeled ssDNA or ssRNA, and the released 3′-FAM mononucleotide products were quantified for calculating the initial rates. All data are the means of three independent experiments.