De-novo sequencing of nucleic acids

A method for the sequencing of a target nucleic acid comprising:

• a) performing a multistage mass spectrometry, comprising
• i) ionizing said target nucleic acid,
• ii) measuring the mass of the ionized target nucleic acid,
• iii) determining the base composition corresponding to the mass of said ionized target nucleic acid,
• iv) fragmenting said ionized target nucleic acid by a collision induced dissociation (CID),
• v) measuring the corresponding mass spectrum of the CID fragments, and
• b) comparing the measured CID mass spectrum of the target nucleic acid measured in step v) with a fraction of all calculated CID mass spectra, wherein each of said calculated CID mass spectra correspond to a base sequence having the base composition determined in step iii),
• wherein the comparison of the measured CID mass spectrum with the calculated CID mass spectra of step b) is performed by an optimization algorithm comprising the evolution steps of:
• aa) choosing a population of parent sequences all having said base composition determined in step iii),
• bb) selecting a fraction of parent sequences from said population of parent sequences, wherein the selection of said fraction of parent sequences is based on the comparison of score values of the calculated CID mass spectra of said population of parent sequences with respect to said measured CID mass spectrum measured in step v),
• cc) producing a population of daughter sequences comprising said fraction of parent sequences and altered sequences obtained by recombination of parent sequences from said fraction of parent sequences, said recombination being performed by exchanging a group of bases between two selected parent sequences of said fraction of parent sequences selected in step bb), wherein said group of bases has the same base composition and
• dd) repeating steps aa) to cc), wherein said population of daughter sequences produced in step cc) is used as the population of parent sequences for the next evolution step,
• wherein said optimization algorithm compares said measured CID mass spectrum successively with said plurality of calculated CID mass spectra and determines a respective score value for each comparison, said score value representing the degree of consistency between said measured CID mass spectrum and said calculated CID mass spectra, and
• wherein the base sequence corresponding to the calculated CID mass spectra yielding the best score value is selected as the base sequence of said target nucleic acid, and said base sequence is presented in a user readable format.