Mass spectrometry of trifluoroacetyl derivatives of nucleosides and hydrolysates of deoxyribonucleic acid

Gas chromatography/mass spectrometric analysis of urinary nucleosides in cancer patients; potential of modified nucleosides as tumour markers

Analysis of urine from cancer patients by capillary gas chromatography/mass spectrometry positively identified 14 urinary nucleosides including several modified nucleosides. Levels of the modified nucleosides 1-methyl-adenosine, 2-methylguanosine, N2,N2-dimethylguanosine and 1-methylinosine as well as the total nucleoside level were elevated in the urine when a malignant tumour was present; the levels of N2,N2-dimethylguanosine were found to correlate with the stage of the cancer.

Mass spectrometry of electrophore-labeled nucleosides. Pentafluorobenzyl and cinnamoyl derivatives

Three structurally similar deoxynucleosides (thymidine, O4-ethylthymidine, and 2'-deoxyuridine) were studied by mass spectrometry as pentafluorobenzyl, cinnamyl, or mixed derivatives. The purpose of the work was to define the usefulness of such derivatives for structural elucidation of deoxynucleosides. The compounds were ionized in three ways: electron capture negative ion, positive ion chemical ionization, and electron impact. For each of the derivatives examined, the combined spectra were well suited for structural elucidation purposes.

Identification of nucleosides in hydrolysates of transfer RNA by high-resolution mass spectrometry

High-resolution mass spectrometry has been investigated as a technique for identification of modified nucleosides in unfractionated hydrolysates of transfer RNA. The method is based on recognition of predetermined sets of exact mass values which are characteristic of individual nucleoside components. Mass spectra are photographically recorded in a non-time-resolved fashion, so that differing rates of nucleoside vaporization are of no consequence. Experimental parameters of sensitivity, spectrometer resolution and rates of vaporization were studied. Under typical conditions, 1-4 micrograms of tRNA are hydrolyzed, converted to volatile trimethylsilyl derivatives, and mass spectra of the resulting mixture recorded during 3 min at resolution 20 000; 75-100% of the minor nucleosides are usually identified in a single recording. The method is complementary to conventional methods of identification which rely on chromatographic mobilities, and can in principle be generally applied to recognition of biologically or chemically modified bases in nucleic acid.

Detection and identification of minor nucleotides in intact deoxyribonucleic acids by mass spectrometry

A mass spectral method is described for the detection and identification of unusual nucleotide residues present in DNAs. Analysis by this method of intact, underivatized DNA from salmon sperm, calf thymus, mouse L-cells, wheat germ, M. lysodeikticus, E. Coli, and the bacteriophages 0X-174, fd, and lamda, yields diagnostic ions for the four common components of DNA as well as characteristic ions for 5-methyldeoxycytidine residues. The spectrum from T2 DNA contains ions indicative of 5-hydroxymethyldeoxycytidine and 5-methyldoxycytidine components but no ions corresponding to deoxycytidine residues. The DNAs of phages fd and 0X-174 also display ion products indicative of N6-methyldeoxyadenosine residues. Additional series of ions in the spectra of all four bacteriophage DNAs suggest the presence of 5-substituted deoxyuridine residues. The detection method exhibits considerable sensitivity in that amounts of DNA as low as 0.01 A260nm units can be used in the analysis, and thus, the procedure should prove of some value in the detection and location of modified components in specific regions of the various genomes by analysis of the appropriate endonuclease restriction fragments.

Stoffwechselprodukte von mikroorganismen. 154. Mitteilung. Nikkomycin, ein neuer hemmstoff der chitinsynthese bei pilzen

From the fermentation broth of Streptomyces tendae Tü 901 a substance was isolated which inhibits the growth of several fungi. The new antibiotic affects the chitchin biosynthesis. Its structure was identified by mass spectrometry of the products obtained after chemical degradation. Nikkomycin is a nucleoside-peptide antibiotic consisting of uracil, an amino hexuronic acid and a new amino acid containing a pyridin ring.