15N relaxation NMR studies of prolyl oligopeptidase, an 80 kDa enzyme, reveal a pre-existing equilibrium between different conformational states.

Open and closed: The characterization of protein mobility is crucial for the understanding of biological functions. We have applied NMR spectroscopy to study the conformational dynamics of the 80 kDa enzyme prolyl oligopeptidase (POP). Our results revealed that POP is highly dynamic and that inhibition of catalytic activity shifts this conformational equilibrium towards a less dynamic state. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.