抄録
Applicability of FAB high-energy-CID MS/MS to structural characterization of two types of tetraphenylporphyrin (TPP)-derivatives was examined. These tetraphenylporphyrin (TPP)-derivatives, 20-hydroxy-2,2-dimethylicosanoyl picket-fence porphyrinatoiron and 20-cholinephosphoryl-2,2-dimethylicosanoyl picket-fence porphyrinatoiron have four 2,2-dimethylicosanamido long-chains in common in their structures, which keep a balance between hydrophobic and hydrophilic properties. The structural difference between the two compounds is that the former has a hydroxyl group at the remote end of the 2,2-dimethylicosanamido long-chain, while the latter has a phosphocholine ester functional group at the remote-end. This structural difference gives rise to different features as well as some analogies in their FAB and the high-energy-CID MS/MS spectra. Differences and analogies in those spectra were also noted between the long-chain porphyrin derivatives we are describing here and the pivaloyl-type porphyrins we reported previously [T. Shibue, H. Kambe, H. Nishide, S. Akashi, N. Dohmae, and Y. Ohashi, Eur. Mass Spectrom., 3, 291-299 (1997)]. By selecting a precursor ion at m/z 476, which corresponds to the 20-cholinephosphoryl-2,2-dimethylicosanoyl group, charge-remote fragmentation was observed. This observation reminded us our previous study on the imidazole-tailed picket-fence porphyrin fragmentations.
