Apparent activation energies of protein-protein complex dissociation in the gas-phase determined by electrospray mass spectrometry

作者：Yefremova Yelena; Melder F Teresa I; Danquah Bright D; Opuni Kwabena F M; Koy Cornelia; Ehrens Alexandra; Frommholz David; Illges Harald; Koelbel Knut; Sobott Frank; Glocker Michael O^*

来源：Analytical and Bioanalytical Chemistry, 2017, 409(28): 6549-6558.

DOI：10.1007/s00216-017-0603-4

• Protein-protein interaction
• Native mass spectrometry
• Ion mobility
• Collision induced dissociation
• Quasi equilibrium conditions

We have developed a method to determine apparent activation energies of dissociation for ionized protein-protein complexes in the gas phase using electrospray ionization mass spectrometry following the Rice-Ramsperger-Kassel-Marcus quasi-equilibrium theory. Protein-protein complexes were formed in solution, transferred into the gas phase, and separated from excess free protein by ion mobility filtering. Afterwards, complex disassembly was initiated by collision-induced dissociation with step-wise increasing energies. Relative intensities of ion signals were used to calculate apparent activation energies of dissociation in the gas phase by applying linear free energy relations. The method was developed using streptavidin tetramers. Experimentally determined apparent gas-phase activation energies for dissociation () of complexes consisting of Fc parts from immunoglobulins (IgG-Fc) and three closely related protein G' variants (IgG-FcaEuro cent protein G'e, IgG-FcaEuro cent protein G'f, and IgG-FcaEuro cent protein G'g) show the same order of stabilities as can be inferred from their in-solution binding constants. Differences in stabilities between the protein-protein complexes correspond to single amino acid residue exchanges in the IgG-binding regions of the protein G' variants.

• 出版日期2017-11