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PHOTOCHEMISTRY AND PHOTOPHYSICS OF GUANINE‐CONTAINING DINUCLEOSIDES
Author(s) -
Morgan James P.,
Callis Patrik R.
Publication year - 1979
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1979.tb07827.x
Subject(s) - phosphorescence , photochemistry , chemistry , guanine , cytosine , thymine , intramolecular force , uracil , triplet state , guanosine , fluorescence , singlet state , hypsochromic shift , quenching (fluorescence) , stereochemistry , molecule , dna , excited state , nucleotide , biochemistry , physics , organic chemistry , quantum mechanics , nuclear physics , gene
— Yields and action spectra are reported for photochemistry. fluorescence. and total lumincscence at 405 nm due to UV excitation (240–300 nm) or dilutc (‐0.1 mM ) solutions or guanosine 5–monophosphate (GMP) and the dinucleosides linking guanine with adenine (ApG and GpA). cytosine (CpG) and uracil (GpU) in neutral ethylene glycol‐water (7:3) glasses at 140–165 K. Phosphorescence lifetimes were determined at 140 K. Less complete data are presented for GpC, UpG and dpGpT. Quantum yields for all three processes were usually found to increase as the excitation wavelength increases. Although intramolecular exciplex formation was not dominant under these conditions interactions were strong enough to frustrate attempts at interpretation of results within the Forster very weak coupling framework. There is evidence that the GMP photochemistry proceeds from the triplet state. Surprisingly, this photochemistry is not quenched in ApG, GpA, and dpGpT at 163 K although the adenine (A) and thymine (T) moieties are known to have lower triplet states. At 140 K the phosphorescence from ApG and GpA was entirely characteristic of A but both G and T components were observed from dpGpT.