Cees Dekker led a team of researchers who succeeded in inventing a method of scanning a protein and all its constituent amino acids. They passed each protein through the nanopore, viewing one amino acid at a time. These groups gave off ion currents due to the various bonds within the peptides. By understanding the connection between the amount of ion current and the content of the protein, they discovered another approach to protein cataloging and sequencing within a cell.
Nanostructure
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How did this happen?
Each protein is a combination of multiple peptides. Each peptide has twenty amino acids that are different in sequence, type, or both. Although a DNA blueprint can also give a detailed content of every protein, it is not so accurate due to post-translational modifications. The impact of this research would be tremendous, as understanding the structure or seeing the structure of the proteins, creates a new approach for research and diagnosis.
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The author of this research, Henry Brinkerhoff, described this method with a water drain analogy. His words created an understanding of the single-protein molecule method, by assuming the amino acids as balls that need to pass through a hole (nanopore) to drain. When the small balls are in the drain, more amount of water (ion current) flows through the drain; when the balls are big, the water passing through is barely in drops. One advantage of this method is that you can view a single peptide over and over again after which you can find the average read, which is 100% accurate. Just like a cashier swipes each Item you order through a barcode, the same way an amino acid in a peptide swipes through a nanopore. This approach supports single-protein scanning, but when you want to scan the whole protein from the beginning again (de novo) it becomes complicated. To simplify this, this team hypothesis characterizes each signal from each peptide; to create a map that clearly shows the expected signals from every sequence.
To understand how amino acid combinations affect the ion current in a nanopore, Alek Aksimentiev demonstrated an experiment on molecular dynamics. This study cannot be neglected because the researchers observed that a change in a single amino acid in a peptide chain creates a different ion current signal. This signifies the level of sensitivity of this method.
Clinical Significance
Clinically, this technique can be used to study the after changes in protein structure that might be involved in cancer, and other diseases. These changes (post-translational modifications) births many varieties, which are referred to as the ‘dark matter of biology.’ If these changes are detected, it would lead to better medical diagnostics.
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Conclusion
The structure of proteins is a very important concern to every human being as most chemical processes in the body are engineered by proteins. The need for single-amino-acid studies is self-evident as new applications are seen on a daily basis.
References
Brinkerhoff, H., Kang, A. S. W., Liu, J., Aksimentiev, A., & Dekker, C. (2021). Multiple rereads of single proteins at single–amino acid resolution using nanopores. Science, 374(6574), 1509–1513. https://doi.org/10.1126/science.abl4381
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