Oligonucleotides molecular mass determination

The error on the measured molecular mass obtained by MALDI varies between 0.01 to 0.05 % for small oligonucleotides. This error increases to 0.5 % or even more for large nucleotides. Indeed, at higher masses the signals from adducts or resulting from the loss of a base are more abundant and cannot be resolved, any more, causing a broadening of the peak. The error on the centroid determination increases. One could consider that the maximum size that can be analysed reasonably by MALDI is around 50 bases for DNA. For RNA more than 100 bases have been analysed with success. [164]... 

MS does not only allow precise determination of the molecular mass of oligonucleotides with their high molecular weight, but does permit sequencing of nucleic acids when using extremely small amounts of sample material. 

The monoisotopic mass is meaningful for low-mass compounds because the elemental composition can be determined from a well-defined isotopic pattern of the molecular ion. The nominal and monoisotopic masses can both be correlated with the most abundant peak in the isotopic cluster. As the mass of a compound, however, increases, the isotopic pattern becomes more synunetrical and extends over many masses [21]. Also, the monoisotopic peak becomes difficult to identify. For high-mass compounds (e.g., proteins and oligonucleotides), the molecular ion profile measured coalesces and becomes a single asymmetric peak. For such compounds, the average mass value is accepted as the molecular mass. 

Determination of the molecular mass of peptides, proteins, and oligonucleotides... 

Mass spectrometric measurements of oligonucleotides and nucleic acids involve the determination of molecular mass, or of the masses of dissociation products of gas-phase ions, which can then be... 

MALDI-MS has found applications in the mass determination of molecules ranging from small peptides, oligosaccharides, and oligonucleotides, to large proteins and synthetic polymers. Polymeric constituents in coal ranging from several hundred molecular weight to 16,000 have been mass analyzed by MALDI, and synthetic polymers of MW up to 70,000 have been reported. 

Covey, T.R. Bonner, R.F. Shushan, B.I. Henion, J.D. The Determination of Protein, Oligonucleotide, and Peptide Molecular Weights by lon-Spray-MS. Rapid Commun. Mass Spectrom. 1988, 2, 249-256. 

Mass spectrometry not only allows precise determination of the molecular weight of oligonucleotides, but also in a direct or indirect way the determination of their sequences. 

The simplest and also most common application of mass spectrometry is the accurate determination of molecular weight to verify the presence of an oligonucleotide of a... 

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