Synopsis: Maintaining the Sequence

Theoretical calculations indicate that an electrospray-based technique could correctly read out the amino acid sequence of protein molecules.
Synopsis figure
W. Maulbetsch et al., Phys. Rev. Appl. (2016)

Sequencing DNA is now routine, but reading out proteins is still challenging and expensive—it can take weeks and cost upwards of $70 per amino acid. Now Derek Stein and colleagues at Brown University, Rhode Island, have studied the feasibility of reading protein sequences by separating off amino acids one-by-one and spraying them into a mass spectrometer. There are many technical challenges that would have to be overcome to realize their method, but the researchers’ calculations indicate that it could work, enabling faster and cheaper sequencing methods for myriad proteins and polymers.

The group considered a row of connected particles—a protein made up of amino acids—traveling down a tube. At the exit of the tube, amino acids are cut off one-by-one, move a short distance, and are then identified by their mass and charge. For successful sequencing, the amino acids must retain their order until the readout process has been completed. The researchers predict this can occur if, as an amino acid is cut from the protein, it is simultaneously pulled away from it—something their calculations show could be done using an electrospray. The directional force imparted by the spray separates the particles, mitigating the effect of the Brownian motion that would otherwise jumble their order.

The team suggests two ways to cleave the amino acids: via laser light or using enzymes. For both methods, cutting has to occur within a narrow distance of the tube’s exit (3 nm for light and 100 nm for enzymes) to ensure the amino acids enter the mass spectrometer in sequence. Realizing this would require pinpoint cutting accuracies—something the researchers say is achievable with current technologies.

This research is published in Physical Review Applied.

–Katherine Wright

Katherine Wright is a Contributing Editor for Physics.


More Features »


More Announcements »

Subject Areas

Biological Physics

Previous Synopsis

Atomic and Molecular Physics

Atomic Line Shape Carries Mark of Quantum Statistics

Read More »

Next Synopsis

Topological Insulators

Topological Insulators Feel the Heat

Read More »

Related Articles

Synopsis: Racing Bacteria
Biological Physics

Synopsis: Racing Bacteria

Bacteria track fast-moving chemical signals by hopping from one chemically favorable region to another. Read More »

Synopsis: Cell Sensing Improves in a Loose Crowd
Biological Physics

Synopsis: Cell Sensing Improves in a Loose Crowd

Cells that communicate with each other can measure chemical concentrations with higher precision if they spread out into a sparse configuration.   Read More »

Focus: Membrane Holes Can Shrink, Grow, or Stay Put
Soft Matter

Focus: Membrane Holes Can Shrink, Grow, or Stay Put

Pores in a polymer film do not change size over time if they have just the right diameter, according to experiments. Read More »

More Articles