The complex and dynamic nature of the proteome makes sensitive and high-throughput protein sequencing challenging. The field awaits methods that could offer the sort of leap next-generation DNA sequencing approaches provided genomics. Researchers at Quantum-Si, a US-based life science research company, have developed a real-time method for high-throughput, single-molecule protein sequencing. The approach involves immobilizing peptides in nanoscale reaction chambers on a semiconductor device. “Dye-labeled amino acid recognizers and aminopeptidases carry out detection of N-terminal amino acids as peptides undergo stepwise cleavage,” explains Brian Reed, head of research at Quantum-Si. The method is paired with a semiconductor chip and compact benchtop device that make highly parallelized, single-molecule fluorescence measurements.
Recognizer proteins rapidly bind and release specific N-terminal amino acids, resulting in a pattern of pulsing that is characteristic for each type of amino acid. “Excitingly, we’ve found that post-translational modifications and single amino acid changes can be readily detected due to the way they modulate these pulsing patterns,” says Reed. Currently, three recognizers can detect seven different amino acids. The detected kinetic signatures also take into account the adjacent downstream amino acids, increasing the information content in the data obtained. The researchers are working to expand the repertoire of amino acid recognizers and aminopeptidases to increase accuracy, sensitivity and the ability to detect a variety of PTMs in order to make the approach broadly applicable.
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