Self-Assembly of the Cephalopod Protein Reflectin

Hydrogen/deuterium exchange (HDX) mass spectrometry (MS) has become a key technique for monitoring structural and dynamic aspects of proteins in solution. This approach relies on the fact that exposure of a protein to D(2)O induces rapid amide H → D exchange in disordered regions that lack stable hydrogen-bonding. Tightly folded elements are much more protected from HDX, resulting in slow isotope exchange that is mediated by the structural dynamics ("breathing motions") of the protein. MS-based peptide mapping is a well established technique for measuring the mass shifts of individual protein segments. This tutorial review briefly discusses basic fundamentals of HDX/MS, before highlighting a number of recent developments and applications. Gas phase fragmentation strategies represent a promising alternative to the traditional proteolysis-based approach, but experimentalists have to be aware of scrambling phenomena that can be encountered under certain conditions. Electron-based dissociation methods provide a solution to this problem. We also discuss recent advances that facilitate the applicability of HDX/MS to membrane proteins, and to the characterization of short-lived protein folding intermediates. It is hoped that this review will provide a starting point for novices, as well as a useful reference for practitioners, who require an overview of some recent trends in HDX/MS.

We present an efficient pipeline enabling high-throughput analysis of protein structure in solution with small angle X-ray scattering (SAXS). Our SAXS pipeline combines automated sample handling of microliter volumes, temperature and anaerobic control, rapid data collection, data analysis, and couples structural analysis with automated archiving. We subjected 50 representative proteins, mostly from Pyrococcus furiosus, to this pipeline, revealing that 30 were multimeric structures in solution. SAXS analysis allowed us to distinguish aggregated and unfolded proteins, define global structural parameters and oligomeric states for most samples, identify shapes and similar structures for 25 unknown structures, and determine envelopes for 41 proteins. We believe that high throughput SAXS is an enabling technology that may change the way that structural genomics research is done.