Analysis of negatively 'charge tagged' DNA by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.
An improvement in detectability and stability of DNA analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) using oligonucleotides modified with a neutralized backbone and a fixed single, positive charge was recently reported. The attachment of the positive charge requires a primary amino group, limiting this approach to accordingly functionalized DNA. The method described here uses backbone neutralized DNA for the same purpose, with a single unmodified phosphate in the DNA backbone carrying the negative charge. Thus, no chemical modification other than neutralizing the remaining charges on the phosphorothioates is required. This is performed in a single methylation step. The enhancement in sensitivity is comparable to that for DNA carrying a single positive charge, interestingly even when using the same non-protonating matrix. The mechanistic implications of these findings regarding the MALDI process are discussed. The DNA derivatization methods presented help to make MALDI-MS of DNA applicable and competitive for genome analysis and medical diagnostics.
Berlin
K
K
Max-Planck-Institute for Molecular Genetics, Department Lehrach, Ihnestrasse 73, 14195 Berlin, Germany.
Gut
I G
IG
D004247:DNA / Q000032:analysis*; D015394:Molecular Structure; D009841:Oligonucleotides / Q000737:chemistry; D010710:Phosphates / Q000737:chemistry; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods; D055672:Static Electricity
D009841:Oligonucleotides; D010710:Phosphates; D004247:DNA