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: Better Signals from Electronic Body Implants
Biological Physics

Synopsis: Better Signals from Electronic Body Implants

The transmission distance of a wireless implant could be tripled by carefully tuning the frequency of the electromagnetic signal it emits. Read More »

Synopsis: How Hairy Tongues Help Bats Drink Nectar
Fluid Dynamics

Synopsis: How Hairy Tongues Help Bats Drink Nectar

Experiments and theory show that hairs on a bat’s tongue allow the animal to drink 10 times more nectar than it could if its tongue were smooth. Read More »

Synopsis: Soft Tissues with Sharp Boundaries
Biological Physics

Synopsis: Soft Tissues with Sharp Boundaries

A model for cellular populations incorporates neighbor-specific interactions to explain sharp boundaries observed around tissues. Read More »

More Articles