Label-Free Imaging of Solid-Phase Peptide Synthesis Products and Their Modifications Tethered in Microspots Using Time-of-Flight Secondary Ion Mass Spectrometry

Time-of-flight secondary ion mass spectrometry is used to analyze solid-phase synthesis products in 60 mu m spots of high-density peptide arrays. As a result, a table of specific fragments for the individual detection of amino acids and their side chain protecting groups within peptides is compiled. The specific signal of an amino acid increases linearly as its number increases in the immobilized peptide. Mass-to-charge ratio values are identified that can distinguish between isomers such as leucine and isoleucine. The accessibility of the N-terminus of polyalanine will be studied depending on the number of its residues. The examples provided in the study demonstrate the significant potential of time-of-flight secondary ion mass spectrometry for high-throughput screening of functional groups and their accessibility to chemical reactions occurring simultaneously in hundreds of thousands of microreactors on a single microscope slide.

Automated summary

Time-of-flight secondary ion mass spectrometry is used to analyze solid-phase synthesis products in high-density peptide arrays. Specific fragments for individual detection of amino acids and their side chain protecting groups within peptides are compiled. The method shows linear increases in specific signals with increasing number of amino acids in the immobilized peptide, and can distinguish between isomers. The study demonstrates the significant potential of the method for high-throughput screening of functional groups and their accessibility in microreactors on a single microscope slide.