Roles of Lysine1 and Lysine7 Residues of Bovine Pancreatic Ribonuclease in the Enzymatic Activity

1) In order to investigate the roles of Lys1 and Lys7 of RNase A in the enzymatic activity, four S-peptide derivatives were prepared and their abilities to activate S-protein were measured. They are 1-norleucine-S-peptide, 7-norleucine S-peptide, 1,7-di-norleucine-S-peptide, and tri-N-acetyl S-peptide. 2) From the analyses of the relative activity and kinetic parameters of RNase S' derivatives with UpU, UpU> p, and UpUpU> p, it was concluded that Lys7 of RNase A is a binding site for 3′-phosphate of UpU > p and the modification or substitution of Lys1 affects the binding of trinucleotide substrate.