Characterization of cationic glycoporphyrins by electrospray tandem mass spectrometry.
Novel cationic porphyrin derivatives having a galactose or a bis(isopropylidene)galactose unit linked directly to a pyridine or to an aminophenyl group were characterized by electrospray tandem mass spectrometry (ESI-MS/MS). The electrospray mass spectra (ESI-MS) show the M(+) ions, since these porphyrins are already monocharged in solution. The fragmentation of these ions under ESI-MS/MS conditions was studied and it was found that elimination of the sugar residue as a radical (-163 or -243 Da) is a common fragmentation pathway. Loss of the sugar unit as a neutral fragment (-162 or -242 Da) and cross-ring fragmentations typical of glyco-derivatives are also observed for the pyridinium glycoporphyrins, but they are absent in the case of ammonium glycoporphyrins. The cationic beta-pyridiniumvinyl porphyrins show an atypical fragmentation due to the cleavage of the C(5)-C(6) bond of the sugar unit. Overall, the different patterns of fragmentation observed in the ESI-MS/MS spectra of the sugar pyridinium porphyrins and of the sugar ammonium phenyl porphyrins can give important information about the type of spacer between the porphyrin and the sugar unit.
Silva
Eduarda M P
EM
Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
Serra
Vanda Vaz
VV
Ribeiro
Anderson O
AO
Tomé
João P C
JP
Domingues
Pedro
P
Faustino
M Amparo F
MA
Neves
M Graça P M S
MG
Tomé
Augusto C
AC
Cavaleiro
José A S
JA
Ferrer-Correia
António J
AJ
Iamamoto
Yassuko
Y
Domingues
M Rosário M
MR
D002412:Cations; D005690:Galactose / Q000032:analysis* / Q000737:chemistry*; D011166:Porphyrins / Q000032:analysis* / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
D002412:Cations; D011166:Porphyrins; D005690:Galactose