Operating principle of peptide sequencing verified

Operating principle of peptide sequencing verified

There are great expectations for this long-awaited technique of peptide analysis.

Sep 15, 2014

A group of researchers at Osaka University have verified the operating principle of peptide sequencing.

Chief researchers in this project:
• Funding Program for World-Leading Innovative R&D on Science and Technology -- KAWAI Tomoji , Specially Appointed Professor
• Department of Bio-Nanotechnology, Institute of Scientific and Industrial Research -- TANIGUCHI Masateru , Professor

Peptide sequences for identifying amino-acid sequences of peptides requiring no chemical processing have not been developed and have been thought of as an unattainable dream. Using a semi-conductor technique, this group of researchers has developed a nanogap electrode --a pair of electrodes with a nanometer gap-- and, using it, succeeded in identifying partial amino-acid sequences of peptides using the electric current flowing through a single amino-acid molecule. This group also succeeded in identifying the post-translational modification phosphotyrosine involved in the process that switches enzymes on and off.

In order to achieve the realization of individualized medicines, methods for analyzing amino acid sequences at a very high speed and at low cost have been sought after with the same being sought in gene analysis. Peptides, in particular, are drug targets and the importance of peptide sequencing is increasing. However, thus far, a chemical-processing-free peptide sequencer has not been developed.

Furthermore, as modified amino acids are deeply involved in causes and conditions of cancer and auto immune diseases, the development of methods for detecting amino-acids at the level of a single molecule has also been sought after. Since peptide sequencing technique for measuring electric resistance in a single molecule works on a principle totally different from heretofore techniques, there are great expectations for this long-awaited technique of peptide analysis.

This group's single-molecule analysis technique has verified a most important concept for developing basic research in the implementation of a practical peptide sequencing technique. Moreover, it is expected that this group's findings will have a tremendous effect in rapidly promoting future research and development.


Post-translational modifications alter the properties of proteins through the cleavage of peptide bonds or the addition of a modifying group to one or more amino acids. These modifications allow proteins to perform their primary biological functions, but single-protein studies of post-translational modifications have been hindered by a lack of suitable analysis methods. Here, we show that single amino acids can be identified using electron tunnelling currents measured as the individual molecules pass through a nanoscale gap between electrodes. We identify 12 different amino acids and the post-translational modification phosphotyrosine, which is involved in the process that switches enzymes on and off. Furthermore, we show that the conductance measurements can be used to partially sequence peptides of an epidermal growth factor receptor substrate, and can discriminate a peptide from its phosphorylated variant.

To learn more about this research, please view the full research report entitled " Detection of post-translational modifications in single peptides using electron tunnelling currents " at this page of the Nature Nanotechnology website.

Related link :

Technical Glossary