Table 1. Kinetic parameters [V_{max(apparent)}, K_m(apparent), and V_{max(apparent)} /K_m(apparent)] in the RNase P-mediated cleavage reactions of ptRNA^Ser or HBV s38 RNA substrate in the presence of different EGSs.

Substrate			Km(µM)			Vmax (apparent)(pmol·min-1)			Vmax(apparent)/Km(apparent)(pmol·µM-1·min-1)			Kd(µM)
ptRNASer			0.020±0.075			0.061±0.025			3.0±0.6
S RNA (s38)
+S-SER			0.60±0.15			0.027±0.011			0.045±0.015			1.8±0.6
+S-SER-C			ND			ND			<0.001			1.9±0.7
+S-C386			0.30±0.10			0.75±0.30			2.5±0.4			0.025±0.005
+S-C386-C			ND			ND			<0.001			0.026±0.005

Multiple-turnover kinetic analyses to determine the values of V_{max(apparent)} and K_m(apparent) were carried out in buffer A (50 mM Tris, pH 7.4, 100 mM NH₄Cl, and 10 mM MgCl₂) at 37°C, as described previously [12,33,34]. To determine the binding affinity (K_d) between substrate s38 and EGSs, binding assays were carried out in the absence of human RNase P in buffer B (50 mM Tris, pH 7.5, 100 mM NH₄Cl, 10 mM MgCl₂, 3% glycerol, 0.1% xylene cyanol, 0.1% bromophenol blue), using a protocol modified from Pyle et al [31]. The values shown are the arithmetic means of five experiments performed in triplicate. ND: not determined.