Kinetic Constants of Ribonuclease F_1 Acetylated at Lysine 62 toward High Molecular Weight RNA

Kinetic constants toward high molecular weight RNA have been determined with native ribonuclease F_1 and the enzyme acetylated at lysine 62. The Michaelis constant and the maximum velocity are 0.75 mg/ml and 0.32 U/nM, respectively, with ribonuclease F_1 and 0.93 mg/ml and 0.13 U/nM, respectively, with the acetylated enzyme. These results suggest that lysine 62 does not constitute a phosphate binding subsite, but somehow participates in the catalytic breakdown of high molecular weight substrates.