RNPA1000 and RNPA2000 inhibit RNase P-mediated ptRNATyr processing in vitro. RNase P activity assays measuring the ability of the enzyme to catalyze conversion of ptRNATyr to tRNATyr in the absence or presence of increasing concentrations (0, 31.25, 62.5, 125, 250, and 500 μM) of RNPA1000 (A) and RNPA2000 (B).