The smallest “ruler” ever has been developed, capable of measuring the width of a single atom within a protein with remarkable precision.
Proteins and other macromolecules often fold incorrectly, impacting their functionality and potentially contributing to conditions like Alzheimer’s disease. To address this issue, accurate measurements of the distances between atoms and clusters within these large biomolecules are crucial.
Researchers have transitioned from using microscopes to map the positions of macromolecules to a groundbreaking method that measures distances within the macromolecules themselves. By utilizing fluorescence, they attached two fluorescent molecules at different points on a larger protein and used a laser beam for illumination. This method allowed the team to measure the distance between the glowing molecules based on the emitted light.
This innovative approach enabled researchers to measure distances between the molecules of several well-studied proteins, with the smallest distance recorded at just 0.1 nanometers—the width of a single atom. Furthermore, this fluorescent ruler proved effective in measuring distances up to 12 nanometers, outperforming many traditional methods.
In their experiments, researchers distinguished between different forms of the same protein, noting a distance of 1 nanometer apart for one shape and 4 nanometers for another. They also conducted measurements on tiny distances within a human bone cancer cell.
The precision achieved stems from various recent technological advancements, including enhanced microscope stability and the use of non-flickering fluorescent molecules that produce distinct and unambiguous signals.
Experts recognize the significance of this technical advancement, though future studies are needed to determine its applicability across various molecules. While the technique demonstrates impressive precision, its resolution may vary when applied to more complex biological systems, with emerging methods also competing in measuring minute distances.
Going forward, researchers aim to refine this technique and explore its potential applications across a wider array of macromolecules.
