title: Water-Mediated Dimerization of Ubiquitin Ions Captured by Cryogenic Ion Mobility-Mass Spectrometry.
abstract: The dynamics, structures, and functions of most biological molecules are strongly influenced by the nature of the peptide's or protein's interaction with water. Here, cryogenic ion mobility-mass spectrometry studies of ubiquitin have directly captured a water-mediated protein-protein binding event involving hydrated, noncovalently bound dimer ions in solution, and this interaction has potential relevance to one of the most important protein-protein interactions in nature. As solvent is removed, dimer ions, viz. [2 M + 14H](14+), can be stabilized by only a few attached water molecules prior to dissociation into individual monomeric ions. The hydrophobic patch of ubiquitin formed by the side chains of Leu-8, Ile-44, and Val-70 meet all the necessary conditions for a protein-protein binding "hot spot," including the requirement for occlusion of water to nearby hydrophilic sites, and it is suggested that this interaction is responsible for formation of the hydrated noncovalent ubiquitin dimer.
authors.affiliation: Department of Chemistry, Texas A&M University , College Station, Texas 77843, United States.
authors.forename: Kelly A
authors.initials: KA
authors.lastname: Servage
authors.affiliation: Department of Chemistry, Texas A&M University , College Station, Texas 77843, United States.
authors.forename: Joshua A
authors.initials: JA
authors.lastname: Silveira
authors.affiliation: Department of Chemistry, Texas A&M University , College Station, Texas 77843, United States.
authors.forename: Kyle L
authors.initials: KL
authors.lastname: Fort
authors.affiliation: Department of Chemistry, Indiana University , Bloomington, Indiana 47405, United States.
authors.forename: David E
authors.initials: DE
authors.lastname: Clemmer
authors.affiliation: Department of Chemistry, Texas A&M University , College Station, Texas 77843, United States.
authors.forename: David H
authors.initials: DH
authors.lastname: Russell
mesh_terms: D019281:Dimerization; D013058:Mass Spectrometry / Q000379:methods*; D025801:Ubiquitin / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D025801:Ubiquitin; D014867:Water
keywords: dimerization; ion mobility-mass spectrometry; ubiquitin