Chemical synthesis and biological activities of partially inosine-substituted 2',5'-oligoadenylates: functional discrimination of three adenine amino groups on 2-5A for the binding to and activation of 2-5A-dependent endonuclease

Binding and activation efficacies to the 2-5A-dependent endonucease by chemically synthesized partially inosine-substituted 2-5A analogs, namely, pppI2'p5'A2'p5'A, pppA2'p5'I2'p5'A and pppA2'p5'A2'p5'I were compared with that of native 2-5A in mouse L cell and human lymphoblastoid cell extracts. The results obtained in this study indicated that the first adenine amino group from the 5' terminus of 2-5A molecule plays critical role in binding to the endonuclease, whereas the third adenine amino group has a function for the activation of this enzyme.