DNA-SEQUENCING BY DELAYED EXTRACTION MATRIX-ASSISTED LASER DESORPTIONIONIZATION TIME-OF-FLIGHT MASS-SPECTROMETRY/

Matrix-assisted laser desorption/ionization (MALDI) time of flight mas s spectrometry was used to detect and order DNA fragments generated by Sanger dideoxy cycle sequencing. This was accomplished by improving t he sensitivity and resolution of the MALDI method using a delayed ion extraction technique (DE-MALDI). The cycle sequencing chemistry was op timized to produce as much as 100 fmol of each specific dideoxy termin ated fragment, generated from extension of a 13-base primer annealed o n 40- and 50-base templates, Analysis of the resultant sequencing mixt ure by DE-MALDI identified the appropriate termination products. The t echnique provides a new non-gel-based method to sequence DNA which may ultimately have considerable speed advantages over traditional method ologies.