Fig. 6: Hydrogen-deuterium exchange provides information on the conformational dynamics within condensates.

Bulk hydrogen lability of protein condensates as a function of t_a was investigated using hydrogen-deuterium exchange via FTIR. Condensates were deposited on the FTIR prism at different t_a, and rate of exchange was measured. HDX can be monitored by changes in the amide I (~1650 cm⁻¹), amide II (~1550 cm⁻¹) (a, b) and amide II’ (~1450 cm⁻¹) (c, d). Black lines represent spectra in H₂O, and coloured lines show changes in spectra after transfer into D₂O. Representative spectra are presented for t_a = 0 h (a, c) and 8 h (b, d); the spectra for the other time points can be found in the supplementary information. e The extent of exchange was monitored over the course of 10 min by taking the integral of the amide II’ peak to represent D₂O uptake. Each sample was internally normalised against the intensity of the amide II peak in H₂O to control for baseline intensity differences, and against denatured FUS. Error bars represent SD f schematic displaying the conformation-dependence on backbone proton-lability: protons in random coil regions exchange rapidly, while those involved in hydrogen bonding and/or folded domains are less labile ⁴⁴. All measurements taken from 3 technical replicates.