Abundant Lysine Methylation and N-Terminal Acetylation in Sulfolobus islandicus Revealed by Bottom-Up and Top-Down Proteomics.

Protein post-translational methylation has been reported to occur in archaea, including members of the genus Sulfolobus, but has never been characterized on a proteome-wide scale. Among important Sulfolobus proteins carrying such modification are the chromatin proteins that have been described to be methylated on lysine side chains, resembling eukaryotic histones in that aspect. To get more insight into the extent of this modification and its dynamics during the different growth steps of the thermoacidophylic archaeon S.

Mass spectrometric de novo sequencing of natural non-tryptic peptides: comparing peculiarities of collision-induced dissociation (CID) and high energy collision dissociation (HCD).

Rationale: Mass spectrometry has shown itself as the most efficient tool for the sequencing of peptides. However, de novo sequencing of novel natural peptides is significantly more challenging in comparison with the same procedure applied for the tryptic peptides. To reach the goal in this case it is essential to select the most useful methods of triggering fragmentation and combine complementary techniques.

Collision-induced dissociation fragmentation inside disulfide C-terminal loops of natural non-tryptic peptides.

Collision-induced dissociation (CID) spectra of long non-tryptic peptides are usually quite complicated and rather difficult to interpret. Disulfide bond formed by two cysteine residues at C-terminus of frog skin peptides precludes one to determine sequence inside the forming loop. Thereby, chemical modification of S-S bonds is often used in "bottom up" sequencing approach.

LC-MS/MS with 2D mass mapping of skin secretions' peptides as a reliable tool for interspecies identification inside Rana esculenta complex.

Identification of species constituting Rana esculenta complex represents a certain problem as two parental species Rana ridibunda and Rana lessonae form their hybrid R. esculenta, while external signs and sizes of the members of this complex are intersected. However the composition of skin secretion consisting mainly of peptides is different for the species of the complex.

Novel cysteine tags for the sequencing of non-tryptic disulfide peptides of anurans: ESI-MS study of fragmentation efficiency.

Mass spectrometry faces considerable difficulties in de novo sequencing of long non-tryptic peptides with S-S bonds. Long disulfide-containing peptides brevinins 1E and 2Ec from frog Rana ridibunda were reduced and alkylated with nine novel and three known derivatizing agents. Eight of the novel reagents are maleimide derivatives.

Matrix-assisted laser desorption/ionization-post source decay fragmentation of cystine- containing amphibian peptides with novel cysteine tags.

Long disulphide-containing peptides brevinins 1E and 2Ec from the skin secretion of the frog Rana ridibunda were reduced and alkylated with ten novel and three known derivatizing agents. Nine of novel reagents are maleimide derivatives. The peptides were also reduced with DTT directly onto the MALDI target without alkylation.