PerspectivePhysics

Single proteins under a diamond spotlight

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Science  06 Mar 2015:
Vol. 347, Issue 6226, pp. 1072-1073
DOI: 10.1126/science.aaa7440

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Summary

Proteins are the workhorse of life. They assemble the structural elements of the cell, catalyze metabolism, regulate cellular functions, and even transcribe and repair DNA. Many of the proteins' functions are related to their physical shape and conformations. For example, protein-folding problems are responsible for a number of diseases, including Alzheimer's (1). It is no wonder that there has long been an effort to determine the structure of proteins. However, only a small fraction of protein structures have so far been determined. In most situations, results from experiments are not sufficient to build the atomic model of a protein from scratch. Even the proteins whose structures have been determined are usually purified proteins that are no longer in their functional environment, so that the key information on how the protein changes shape to perform its innate function can only be inferred. The solution is to image individual proteins in living cells in real time as they go about their business of sustaining life. An important milestone toward this goal is reported by Shi et al. on page 1135 of this issue (2). They show that motions of a segment of a single protein are inferred by the magnetic signal of a nuclear spin on a nitroxide spin label located 10 nm away from a diamond nanomagnetometer.