title: Stability of a Transient Protein Complex in a Charged Aqueous Droplet with Variable pH.
abstract: Electrospray ionization mass spectrometry (ESI-MS) has the potential to become a high-throughput robust experimental method for the detection of protein-protein equilibrium constants. Poorly understood processes that affect the stability of weak noncovalent protein complexes in the intervening droplet environment are a significant factor that precludes the advancement of the method. We use molecular dynamics to study the stability of a ubiquitin and ubiquitin-associated domain complex (RCSB PDB code 2MRO ) in an aqueous droplet with changing size and charge concentration. We present evidence that a weak protein complex changes conformation and may dissociate in shrinking droplets. Then, the droplets containing these dissociated proteins divide. Our findings suggest that in some cases ESI-MS does not measure the correct association constants. The study intends to stimulate research for systematic development of experimental protocols that stabilize weakly bound protein interfaces in droplets.
authors.affiliation: Department of Chemistry, The University of Western Ontario , London, Ontario N6A 5B7, Canada.
authors.forename: Myong In
authors.initials: MI
authors.lastname: Oh
authors.affiliation: Department of Chemistry, The University of Western Ontario , London, Ontario N6A 5B7, Canada.|Department of Chemistry, University of Cambridge , Lensfield Road, Cambridge CB2 1EW, United Kingdom.
authors.forename: Styliani
authors.identifier: http://orcid.org/0000-0001-8869-4155
authors.initials: S
authors.lastname: Consta
mesh_terms: D000818:Animals; D006863:Hydrogen-Ion Concentration; D056004:Molecular Dynamics Simulation; D011487:Protein Conformation; D055550:Protein Stability; D011506:Proteins / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D025801:Ubiquitin / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D011506:Proteins; D025801:Ubiquitin; D014867:Water