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. Author manuscript; available in PMC: 2013 May 23.
Published in final edited form as: J Am Chem Soc. 2012 Apr 10;134(20):8543–8550. doi: 10.1021/ja3004655

Figure 7.

Figure 7

Pressure effect on the hydration of ubiquitin. Panel A shows overlay of ribbon representations of the ambient pressure crystal structure51 (1UBQ) in gray and the 3 kbar solution structure31 (1V81) in orange. In free aqueous solution, the amide N-H of Q2, K6, E16, G47 and V70 show NOE cross peaks to water at high pressure but not at ambient pressure. They are located in regions that have the pressure induced structural change. Panel B shows a rendering of the surface of the ambient pressure crystal structure in gray, illustrating the surface pocket that exposes the amide hydrogen of L50 to solvent (shown as a blue sphere). The 3 kbar structure was aligned to 1UBQ and the side chain conformations of Q49 shown in stick representation for both 1UBQ (gray) and the 10 conformers in the 3 kbar structural ensemble (orange). This side chain undergoes a rearrangement at high pressure that fills the pocket, thereby burying the L50 amide hydrogen, consistent with the loss of an NOE from this site to the water measurements in the NOESY spectra shown in Figure 6.