Features of Tryptic Peptides Providing Their Detection and Identification by MALDI Mass Spectrometry

Characteristics of tryptic peptides that provide the detection and identification of these compounds and corresponding proteins by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry with α-cyano-4-hydroxycinnamic acid as a matrix are determined and discussed. Twenty-five proteins are identified; the features of reliably identified peptides are compared to those of the compounds that might be produced by trypsinolysis but were not detected. Two key factors enhancing a possibility of the detection of tryptic peptides are determined. One refers to the basicity of peptides in the gas phase, which is the highest for peptides with the C-terminal arginine residue; this reason for the emergence of significant analytical signals is well known. Another factor contributing to the ionization of peptides in study under MALDI conditions is their hydrophilicity. This result did not correlate with the most conclusions of earlier relevant studies discussed in the article.