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Folding determinants of disulfide bond forming protein B explored by solution nuclear magnetic resonance spectroscopy
Author(s) -
Hwang Soyoun,
Hilty Christian
Publication year - 2011
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.22877
Subject(s) - chemistry , folding (dsp implementation) , crystallography , circular dichroism , nuclear magnetic resonance spectroscopy , protein secondary structure , protein folding , transmembrane protein , micelle , protein structure , peptide , protein tertiary structure , transmembrane domain , membrane protein , membrane , stereochemistry , aqueous solution , biochemistry , receptor , electrical engineering , engineering
The two‐stage model for membrane protein folding postulates that individual helices form first and are subsequently packed against each other. To probe the two‐stage model, the structures of peptides representing individual transmembrane helices of the disulfide bond forming protein B have been studied in trifluoroethanol solution as well as in detergent micelles using nuclear magnetic resonance (NMR) and circular dichroism spectroscopy. In TFE solution, peptides showed well‐defined α‐helical structures. Peptide structures in TFE were compared to the structures of full‐length protein obtained by X‐ray crystallography and NMR. The extent of α‐helical secondary structure coincided well, lending support for the two‐stage model for membrane protein folding. However, the conformation of some amino acid side chains differs between the structures of peptide and full‐length protein. In micellar solution, the peptides also adopted a helical structure, albeit of reduced definition. Using measurements of paramagnetic relaxation enhancement, peptides were confirmed to be embedded in micelles. These observations may indicate that in the native protein, tertiary interactions additionally stabilize the secondary structure of the individual transmembrane helices. Proteins 2011. © 2011 Wiley‐Liss, Inc.