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It has been recently shown that in some proteins, tertiary‐structure dynamics occur surprisingly fast, that is on the microsecond or sub‐millisecond time scales. In this State of the Art Review, we discuss how such ultrafast domain motions relate to the function of caseinolytic peptidase B (ClpB), a AAA+ disaggregation machine. ClpB is a large hexameric protein that collaborates with cellular chaperone machinery to rescue protein chains from aggregates. We used single‐molecule FRET spectroscopy to capture the dynamics of essential structural elements within this machine. It was found that the middle domain of ClpB, known to act as its activator, toggles between two states much faster than the overall activity cycle of the protein, suggesting a novel mode of continuous, tunable switching. Motions of the N‐terminal domain were observed to restrict the conformational space of the M domain in the absence of a substrate protein, thereby preventing it from tilting and spuriously activating ClpB. Finally, microsecond dynamics of pore loops responsible for substrate pulling through ClpB's central channel, together with their response to specific perturbations, point to a Brownian‐ratchet mechanism for protein translocation. Based on our findings, we propose a two‐time‐scale model for the activity of ClpB, in which fast conformational dynamics affect slower functional steps, determined by ATP hydrolysis time. Future work on this and other proteins is likely to shed further light on the role of ultrafast dynamics on protein function. [ABSTRACT FROM AUTHOR]

The use of confocal Raman microscopy is applied to the study of whey-protein-stabilized oil-in-water emulsions. The stability of emulsions is an important parameter for many applications and is dependent on several factors including protein content and particle size. Emulsions were prepared with varying particle size ranging from 0.8 to 10.0 µm. Changes in sample volume due to laser-induced heating were monitored and correlated to protein content in samples and to particle diameters. It was found that samples with the lowest protein content and larger particle diameters experienced the largest volume changes. The newly developed approach is of a potential predictive use. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]