Fast Local Backbone Dynamics of Encapsulated Ubiquitin

• Published in: Journal of the American Chemical Society 2006-08, Vol.128 (30), p.9580-9581
• Main Authors: Simorellis, Alana K, Flynn, Peter F
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Intermolecular dynamics; Intermolecular phenomena; Micelles; Models, Molecular; Molecular biophysics; Surface-Active Agents - chemistry; Ubiquitin - chemistry
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja061705p

Backbone dynamics of ubiquitin confined within AOT reverse micelles have been evaluated based on analysis of 15N NMR relaxation data. Results indicate that upon encapsulation the protein experiences a slight overall increase in the value of the order parameter, S 2, indicating a restriction in the average amplitude of fast local N−H bond vector motion. The largest increases in S 2 upon encapsulation were concentrated in the region of β-sheet 2 and, additionally, at the transitions of secondary structure motifs and loop regions. In addition, statistical analysis of the residue average ratio of the 15N longitudinal and transverse NMR relaxation time constants indicates that chemical exchange contributions to relaxation are consistent with previous aqueous studies. Earlier studies have demonstrated that native protein structure can be maintained in the encapsulated state. These results presented here establish that the dynamical behavior of encapsulated ubiquitin is likewise nativelike and adds important new observations regarding the enhancement of protein stability under confinement.