Chemical modification studies suggest that two residues of bovine pancreatic ribonuclease A (RNase A), Lys-41 and Asp-121, are important for catalysis. Three mutants of RNase A have been prepared, two point mutants with Lys-41 altered to Arg-41 and Asp-121 altered to Glu-121, and a double mutant where both residues are altered. The Lys-41 Arg mutant has ca. 2% the calatylic activity (kcalKm) of the native protein, while the Asp-121 Glu mutant has ca. 17% the catalytic activity of the native protein. The double mutant has catalytic activity comparable to the Lys-41 Arg mutant. © 1991.
Trautwein, K., Holliger, P., Stackhouse, J., & Benner, S. A. (1991). Site-directed mutagenesis of bovine pancreatic ribonuclease: Lysine-41 and aspartate-121. FEBS Letters, 281(1–2), 275–277. https://doi.org/10.1016/0014-5793(91)80410-5