Analysis of negatively ‘charge tagged’ DNA by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

✍ Scribed by Kurt Berlin; Ivo G. Gut

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 91 KB
• Volume: 13
• Category: Article
• ISSN: 0951-4198
• DOI: 10.1002/(sici)1097-0231(19990915)13:17<1739::aid-rcm708>3.0.co;2-7

✦ Synopsis

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.