Coulomb instability of multicharged proteins

Joshua Jortner, Isidore Last, Yaacov Levy

Research output: Contribution to journalArticlepeer-review

Abstract

We studied the energetics and fragmentation patterns of multicharged (A+)n Morse clusters (n = 55-321), with a total cluster charge Z = n. The Morse pair-potential parameters were characterized by the dissociation energy D = 1-10 eV, range parameter α = 1-3 Å-1, and interatomic equilibrium separation Re = 1-3 Å. The potential energies ε (per particle) of these multicharged Morse clusters at their equilibrium configuration (with bond length r 0) were analyzed in terms of the liquid drop model. This resulted in the relation ε =(āC0/r0)n 2/3+(āv0D/αr0) +[ās0D/(αr0)3/2]n -1/3, where the reduced parameters āC0 (for the Coulomb energy), āv0 (for the interior energy) and ās0 (for the surface energy) are independent of the Morse pair-potential parameters. The Rayleigh fissibility parameter X = E(Coulomb)/2E(surface), which determines the fragmentation pattern (i.e., X < 1 for cluster fission and X > 1 for Coulomb explosion), was expressed in the form X=(Z2/n)[(2ās 0C0)(D/α3/2r 01/2)]-1. The application of this result to the Coulomb instability of multicharged globular proteins reveals that X < 1 for the currently available data. The dominating fragmentation channel is expected to involve spatially anisotropic protein fission into a small number of large fragments, rather than spatially isotropic protein Coulomb explosion into a large number of small fragments.

Original languageEnglish
Pages (from-to)184-190
Number of pages7
JournalInternational Journal of Mass Spectrometry
Volume249-250
DOIs
StatePublished - 1 Mar 2006

Keywords

  • Coulomb explosion
  • Liquid drop model
  • Morse cluster
  • Multicharged protein

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