COMPLEX FORMATION BETWEEN PYRENE AND THE NUCLEOTIDES GMP, CMP, TMP AND AMP

Pyrene has been found to form ground and excited electronic state complexes of 1:1 stoichi-ometry with GMP, CMP, TMP and AMP. The values of their ground state association constants are 45 M^-1, 13M^-1, 14 M^-1, and 52 M^-1 respectively. The fluorescence of pyrene is strongly quenched by GMP, CMP, and TMP but only slightly by AMP. Fluorescence quenching analysis has yielded the values 87M^-1, 73 M^-1, and 154 M^-1 for the excited state association constants with GMP, CMP, and TMP, respectively. The corresponding values for the excited state second-order rate constant for complex formation are: 3.3 times 10⁹M^-1 s^-1 4.1 times 10⁹M^-1 s^-1, and 4.0 times 10⁹M^-1 s^-1. The probabilities of complex formation per collision between an excited pyrene molecule and a nucleotide are: 0.52, 0.64, and 0.63. The values for the excited state rate constant for dissociation of the complex are: 3.8 times 10⁷s^-1 5.6 times 10⁷s^-1, and 2.6 times 10⁷s^-1. The possibility is discussed that partial transfer of charge from pyrene to nucleotide may be playing a role in the complex formation process.