Ribosyl-diphthamide: Confirmation of structure by fast atom bombardment mass spectrometry |
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| Authors: | James W Bodley Roger Upham Frank W Crow Kenneth B Tomer Michael L Gross |
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| Institution: | 1. Department of Biochemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA;2. Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA;3. Department of Chemistry, University of Nebraska, Lincoln, Lincoln, Nebraska 68588 USA |
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| Abstract: | Diphtheria toxin inactivates protein synthesis elongation factor 2 by attaching ADP-ribose to an unusual post-translational amino acid derivative, diphthamide, in the factor. Previously, we prepared ribosyl-diphthamide from the ADP-ribosyl-factor and proposed on the basis of NMR spectral analysis that it is 1-α-d-ribofuranosyl-2-3-carboxyamido-3-(trimethylammonio)propyl]histidine N. J. Oppenheimer, and J. W. Bodley, (1981) J. Biol. Chem.256, 8579–8581 and op. cit.]. Now, using fast atom bomardment mass spectrometry, the intact cation of ribosyl-diphthamide has been observed in the gas phase. The theoretical mass of the structure proposed for ribosyl-diphthamide uniquely agrees with the observed mass of the inact cation of the compound to within 2 ppm. Collisional activation decomposition mass spectral analysis provided additional structural confirmation. Thus, although the compound has not been synthesized, all available evidence appears uniquely consistent with the structure of ribosyl-diphthamide previously proposed. |
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| Keywords: | To whom correspondence should be addressed |
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