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E. LEHMANN and R. ZENOBI
pIe preparation conditions, such as the nature of the matrix or the matrix analyte
ratio. Once this window is found, experiments involving, for example, pH or oligodeoxynucleotide sequence variations can be performed. However, if a change
of the experimental conditions prohibits observation, no conclusions can be
drawn. An example is the above described experiment involving an oligodeoxynucleotide sequence change: the experimental conditions adequate for the
sequences d(TTGTT) and d(TTATT) were not adequate for d(ACGCC). No conclusion on the sequence-specificity of Zn-p55Fl can therefore be drawn. Future
work has to concentrate on finding more generally usable experimental conditions.
3
Conclusions
In the present study on zinc finger peptide complexation, we demonstrated that
MALD! MS is suitable for the detection of specific biomolecule-metal ion and
noncovalent complexes. The specificity can be proven by carefully designed
chemical controls, such as the variation of pH or competition experiments. We
could also show that MALDI mass spectra reflect solution-phase chemistry. In
this sense, we showed that it is possible to qualitatively study metal-binding
properties of peptides and the pH dependence of the corresponding complexes.
Furthermore, the experiment on the effect of chemical modifications of p55Fl on
the formation of the Zn-p55Fl-oligodeoxynucleotide complex revealed that
MALD! MS is a potential method for rapidly screening antiviral HIV agents. In
order to establish MALD! as a reliable method for detecting noncovalent complexes consisting of molecules of different chemical classes, future work has to
focus on finding more generally usable experimental conditions, such as MALDI
matrices allowing simultaneous detection of the different classes of compounds.
4
Acknowledgements
EL gratefully acknowledges a Kekule-stipend from the Fonds der Chemischen
Industrie (Germany). The authors thank Stefan Vetter for the synthesis of p55Fl
and many helpful discussions as well as the Kommission fur Technologie und
Innovation (project 3165.1), Switzerland, for financial support.
References
Bahr U, Deppe A, Karas M, Hillenkamp F, Giessmann U (1992) Mass spectrometry of synthetic polymers by UV MALDI. Anal. Chern. 64: 2866-2869
Cohen LRH, Strupat K, Hillenkamp F (1997) Analysis of quarternary protein ensembles by MALDI
MS. J Am. Soc. Mass Spectrom. 8: 1046-1052
Fasman GD (1996) Circular Dichroism and the Conformational Analysis of Biomolecules. Plenum
Press, New York
Fitzgerald MC, Parr GR, Smith LM (I993) Basic matrices for MALDI MS of proteins and oligonucleotides. Anal Chern 65: 3204-3211
Glocker MO, Bauer SHJ, Kast J, Volz J, Przybylski M (1996) Characterization of specific noncovalent
protein complexes by UV MALDI MS. J Mass Spectrom 31: 1221-1227
E. LEHMANN and R. ZENOBI
pIe preparation conditions, such as the nature of the matrix or the matrix analyte
ratio. Once this window is found, experiments involving, for example, pH or oligodeoxynucleotide sequence variations can be performed. However, if a change
of the experimental conditions prohibits observation, no conclusions can be
drawn. An example is the above described experiment involving an oligodeoxynucleotide sequence change: the experimental conditions adequate for the
sequences d(TTGTT) and d(TTATT) were not adequate for d(ACGCC). No conclusion on the sequence-specificity of Zn-p55Fl can therefore be drawn. Future
work has to concentrate on finding more generally usable experimental conditions.
3
Conclusions
In the present study on zinc finger peptide complexation, we demonstrated that
MALD! MS is suitable for the detection of specific biomolecule-metal ion and
noncovalent complexes. The specificity can be proven by carefully designed
chemical controls, such as the variation of pH or competition experiments. We
could also show that MALDI mass spectra reflect solution-phase chemistry. In
this sense, we showed that it is possible to qualitatively study metal-binding
properties of peptides and the pH dependence of the corresponding complexes.
Furthermore, the experiment on the effect of chemical modifications of p55Fl on
the formation of the Zn-p55Fl-oligodeoxynucleotide complex revealed that
MALD! MS is a potential method for rapidly screening antiviral HIV agents. In
order to establish MALD! as a reliable method for detecting noncovalent complexes consisting of molecules of different chemical classes, future work has to
focus on finding more generally usable experimental conditions, such as MALDI
matrices allowing simultaneous detection of the different classes of compounds.
4
Acknowledgements
EL gratefully acknowledges a Kekule-stipend from the Fonds der Chemischen
Industrie (Germany). The authors thank Stefan Vetter for the synthesis of p55Fl
and many helpful discussions as well as the Kommission fur Technologie und
Innovation (project 3165.1), Switzerland, for financial support.
References
Bahr U, Deppe A, Karas M, Hillenkamp F, Giessmann U (1992) Mass spectrometry of synthetic polymers by UV MALDI. Anal. Chern. 64: 2866-2869
Cohen LRH, Strupat K, Hillenkamp F (1997) Analysis of quarternary protein ensembles by MALDI
MS. J Am. Soc. Mass Spectrom. 8: 1046-1052
Fasman GD (1996) Circular Dichroism and the Conformational Analysis of Biomolecules. Plenum
Press, New York
Fitzgerald MC, Parr GR, Smith LM (I993) Basic matrices for MALDI MS of proteins and oligonucleotides. Anal Chern 65: 3204-3211
Glocker MO, Bauer SHJ, Kast J, Volz J, Przybylski M (1996) Characterization of specific noncovalent
protein complexes by UV MALDI MS. J Mass Spectrom 31: 1221-1227