Protein Motion Capture

A pair of studies could pave the way for researchers to use thioamides, barely perceptible molecular probes, to track the protein-folding faux pas associated with diseases. E. James Petersson and his team at the University of Pennsylvania previously used thioamides, which differ from a protein’s amide by one oxygen-to-sulfur swap, as fluorescence-quenching probes. The probes adjust fluorescence intensity depending on a protein’s movements. They can be dropped unobtrusively into many locations on a protein, providing more detailed information than bulky probes that can fit only into one or two spots. Now, the researchers have discovered that thioamides work with fluorophores that don’t overlap with a protein’s intrinsic fluorescence (J. Am. Chem. Soc., DOI: 10.1021/ja3005094). His team also made thioamides compatible with a protein assembly method called native chemical ligation, which enabled the study of α-synuclein, a protein implicated in Parkinson’s disease (J. Am. Chem. Soc., DOI: 10.1021/ja2113245). Petersson says he’d like to improve the technique so it can easily insert thioamides in the middle of a protein; so far it works best for the ends.