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Fluorescent derivatives of nucleotides. Metal ion interactions and pH dependency.
Metadata
Journalbiophysical journal3.854Date
1979-Feb
Type
Research Support, U.S. Gov't, P.H.S.
Journal Article
Volume
1979-Feb / 25 : 263-75
Author
Vanderkooi JM , Weiss CJ , Woodrow GV
DoiPMIDMESH
Adenosine Diphosphate
Adenosine Monophosphate
Adenosine Triphosphate
Cations
Chemical Phenomena
Chemistry
Ethenoadenosine Triphosphate
Fluorescent Dyes
Hydrogen-Ion Concentration
Kinetics
Mathematics
Metals
Spectrometry, Fluorescence
Abstract
The fluorescence parameters of ethenoadenosine derivatives are influenced by metal cations and pH, as summarized here. The pH profile of ethenoadenosine determined by fluorescence intensity gives a normal titration curve and is not affected by ionic strength. In contrast, the pH titration curves of etheno-ATP, etheno ADP, and etheno AMP depend upon ionic strength. At high ionic strength normal curves are obtained, whereas at low ionic strength anomalies are obtained; this suggests that the phosphates can interact with the ring, possibly by hydrogen binding to the ring nitrogens. The room temperature fluorescence of ethenoadenosine occurs from the base form, although excitation of either the acid or base forms can contribute to the emission. This result can be explained if the excited state pK is lower than the ground state pK, and if deprotonation occurs within the time scale of the excited state. At low pH values the fluorescence lifetime of the base form is dependent upon the buffer concentration, indicating that the reverse reaction, protonation, occurs. The affinity constants for the binding of metals to the ethenoadenosine phosphates resemble those for the corresponding adenosine phosphates. Ni(II) and Co(II) are more effective than Mn(II) in quenching the fluorescence of ethenoadenosine phosphates; this result is predicted by Förster's theory for energy transfer based upon the overlap between donor emission spectrum and acceptor absorption spectrum. The diamagnetic ions Mg(II), Ca(II), and Zn(II) do not appear to affect the fluorescence of the ethenoadenosine phosphates directly, but rather to affect the conformation of the molecule, thereby affecting the quantum yield.
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3.9
Biophys Jbiophysical journal
Metadata
LocationUnited States
FromCELL PRESS

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