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The AAA+ ATPase Vps4 disassembles ESCRT-III and is essential for HIV-1 budding and other pathways. Vps4 is a paradigmatic member of a class of hexameric AAA+ ATPases that disassemble protein complexes without degradation. To distinguish between local displacement versus global unfolding mechanisms for complex disassembly, we carried out hydrogen/deuterium exchange during Saccharomyces cerevisiae Vps4 disassembly of a chimeric Vps24-2 ESCRT-III filament. EX1 exchange behavior shows that Vps4 completely unfolds ESCRT-III substrates on a time scale consistent with the disassembly reaction. The established unfoldase ClpX showed the same pattern, thus demonstrating a common unfolding mechanism. Vps4 hexamers containing a single cysteine residue in the pore loops were cross-linked to ESCRT-III subunits containing unique cysteines within the folded core domain. These data support a mechanism in which Vps4 disassembles its substrates by completely unfolding them and threading them through the central pore.

With the extensive use of hydrogen energy, hydrogen separation membranes with proton–electron mixed conductors have broad application prospects in hydrogen separation and purification. Herein, La1.85M0.15Ce2O7−δ (M = Li, Na, K, Rb, and Cs; LMC) proton conductors are prepared. The electron paramagnetic resonance, Raman, and X‐ray photoelectron spectroscopy results indicate that the proposed method of replacing part of the La3+ in La2Ce2O7−δ with alkali metal ions produces more oxygen vacancies, which provides more possibilities for ion transport. Among them, La1.85Rb0.15Ce2O7−δ (LRC) exhibits the highest oxygen vacancy concentration. In addition, as the radius of the alkali metal doping ions increases, the corresponding LMC grains also increase. However, an excessively large ionic radius (Cs+) can hinder grain growth. LRC has the largest ionic radius, indicating that it has a smaller grain boundary resistance. This results in the maximum conductivity of the LRC (2.99 × 10−2 S cm−2) in the atmosphere of wet 20% H2 + 80% N2 at 900 °C. Similarly, in the hydrogen permeability test, the LRC exhibits the highest hydrogen flux (2.74 × 10−9 mol cm−2 s−1) at 900 °C. Moreover, an increase in temperature and hydrogen partial pressure on the feed side can promote hydrogen permeability. Therefore, it is a potential material for ceramic hydrogen separation membranes. [ABSTRACT FROM AUTHOR]