PICOLINIC-ACID AS A MATRIX FOR LASER MASS-SPECTROMETRY OF NUCLEIC-ACIDS AND PROTEINS

We found that picolinic acid is a very good matrix for matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry of oligonucleotides, proteins and tRNA. Among the oligonucleotides, pi colinic acid was shown to be effective for homo-oligonucleotides, d(G) 40 and d(C)60, and for mixed-base oligonucleotides up to 190 bases. In the case of the single-stranded oligonucleotides, and of double-stran ded ones as well, only parent ions corresponding to single-stranded DN A were observed. The efficiency for MALDI of oligonucleotides using th e picolinic acid matrix was superior to that using 3-hydroxypicolinic acid. MALDI of transfer RNA phenylalanine-specific (tRNA(Phe)), a 76-b ase ribonucleic acid, was detected with a signal-to-noise ratio of > 1 0. By comparison with 3-hydroxypicolinic acid the results with picolin ic acid are notably superior for all oligonucleotides.