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

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Abstract
—: 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.
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