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Plant annexins form calcium‐independent oligomers in solution
Author(s) -
Hofmann Andreas,
Ruvinov Sergei,
Hess Sonja,
Schantz Rodolphe,
Delmer Deborah P.,
Wlodawer Alexander
Publication year - 2002
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.4770102
Subject(s) - trimer , sedimentation equilibrium , size exclusion chromatography , dimer , ultracentrifuge , annexin , monomer , chemistry , calcium , analytical ultracentrifugation , chromatography , equilibrium constant , ultrafiltration (renal) , biophysics , membrane , yield (engineering) , elution , biochemistry , biology , in vitro , inorganic chemistry , materials science , polymer , organic chemistry , metallurgy , enzyme
The oligomeric state in solution of four plant annexins, namely Anx23(Ca38), Anx24(Ca32), Anx(Gh1), and Anx(Gh2), was characterized by sedimentation equilibrium analysis and gel filtration. All proteins were expressed and purified as amino‐terminal His n fusions. Sequencing of the Anx(Gh1) construct revealed distinct differences with the published sequence. Sedimentation equilibrium analysis of Anx23(Ca38), Anx24(Ca32), and Anx(Gh1) suggests monomer–trimer equilibria for each protein with association constants in the range of 0.9 × 10 10 −1.7 × 10 11 M −2 . All four proteins were subjected to analytical gel filtration under different buffer conditions. Observations from this experiment series agree quantitatively with the ultracentrifugation results, and strongly suggest calcium independence of the annexin oligomerization behavior; moreover, binding of calcium ions to the proteins seems to require disassembly of the oligomers. Anx(Gh2) showed a different elution profile than the other plant annexins; while having only a very small trimer content, this annexin seems to exist in a monomer–dimer equilibrium in solution.