Synthetic Spectroscopic Models Related to Coenzymes and Base Pairs, VII. Stacking Interactions in tRNA; the ``Bend'' at Dimethylguanosine

We have examined the stacking interactions of N2-dimethylguanosine with the nucleosides, e.g., adenosine and cytidine, found adjacent to it in certain tRNA's, by the use of model compounds in which the trimethylene bridge was substituted for the ribose-phosphate-ribose linkage. From the hypochr...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1970-04, Vol.65 (4), p.1025-1032
Main Authors: Iwamura, Hajime, Leonard, Nelson J., Eisinger, Josef
Format: Article
Language:English
Subjects:
Absorption spectra
Adenine - chemical synthesis
Aqueous solutions
Biochemistry
Biological Sciences: Biochemistry
Chromophores
Cytosine - chemical synthesis
Fluorescence
Luminescent Measurements
Models, Structural
Molecules
Nucleosides
Phosphorescence
Purines
Purinones - chemical synthesis
RNA, Transfer
Spectrophotometry
Transfer RNA
Ultraviolet Rays
Wavelengths
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Summary:We have examined the stacking interactions of N2-dimethylguanosine with the nucleosides, e.g., adenosine and cytidine, found adjacent to it in certain tRNA's, by the use of model compounds in which the trimethylene bridge was substituted for the ribose-phosphate-ribose linkage. From the hypochromism exhibited by synthetic 9-[3-(aden-9-yl)propyl]-2-dimethylaminopurin-6-one (IV) and by 9-[3-(cytos-1-yl)propyl]-2-dimethylaminopurin-6-one in aqueous solution (VI) it is apparent that the interaction is at least as great between the N2-dimethylguanine moiety and adenine or cytosine as between guanine and these two bases. The fluorescence and phosphorescence emission spectra were obtained in ethylene glycol-water glass at 80 degrees K. The exciplex fluorescence observed for both bi-molecules (IV and VI) containing the N2-dimethylguanine unit provides further evidence for stacked chromophores.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.65.4.1025