Cross-validation of distance measurements in motile proteins reveals sure inconsistencies

The researchers from PD Dr. Gregor Hagelueken’s group on the Institute of Structural Biology of the UKB used so-called PELDOR spectroscopy to review the motion of so-called substrate-binding proteins. These proteins seize their substrate and transport it to a selected location within the cell. To watch this exactly, the researchers connected tiny magnets – the researchers name them “spin labels” – to the proteins and measured distances which can be solely a couple of billionth of a meter lengthy.

They then transmitted their outcomes to the analysis group of Prof. Dr. Thorben Cordes at LMU Munich. There, comparative measurements have been carried out utilizing so-called FRET spectroscopy. Tiny dye molecules have been used as a substitute of spin labels.

“Though each strategies are used very often, nobody has but systematically investigated whether or not the outcomes are actually comparable,” says Hagelueken.

Though it turned out that the measurement outcomes have been comparable usually, the researchers encountered inconsistencies in two instances.

We then totally investigated what precipitated the variations and located what we have been on the lookout for. In a single case, it turned out that the dye molecules caught to the protein and thus falsified the measurement.”

Martin Peter, Bonn post-doctoral researcher

Within the second case, the addition of a kind of antifreeze, which was crucial due to the low measurement temperature of beneath -220 levels Celsius, led to sudden deviations.

“We have been in a position to present that regardless of the excessive accuracy of the strategies, re-measuring with one other nano ruler is all the time a good suggestion,” Hagelueken says.

Journal reference:

Peter, M.F., et al. (2022) Cross-validation of distance measurements in proteins by PELDOR/DEER and single-molecule FRET. Nature Communications.



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