Nanometric distance measurements between Mn(ii)DOTA centers.
Pulse electron-electron double resonance (PELDOR) is a versatile technique for probing the structures and functions of complex biological systems. Despite the recent interest in high-spin metal-ions for high field/frequency applications, PELDOR measurements of Mn(ii) remain relatively underexplored. Here we present Mn(ii)-Mn(ii) PELDOR distance measurements at 94 GHz on polyproline II (PPII) helices doubly spin-labeled with Mn(ii)DOTA, which are distinguished by their small zero-field interaction. The measured Mn-Mn distances and distribution profiles were in good agreement with the expected values from molecular models. Additional features in the frequency-domain spectra became apparent at certain combinations of detect and pump frequencies. Spin-Hamiltonian calculations showed that they likely arose from contributions from the pseudo-secular component of the dipolar interaction that were found to be non-negligible for Mn(ii)DOTA. However, the influence of the pseudo-secular component on the distance distribution profiles apparently was limited. The results show the potential of Mn(ii)DOTA spin labels for high-field PELDOR distance measurements in proteins and other biological systems.
Institute for Integrative Biology of the Cell (I2BC), Department of Biochemistry, Biophysics and Structural Biology, Université Paris-Saclay, CEA, CNRS UMR 9198, Gif-sur-Yvette, F-91191, France. sun.un@cea.fr.
H Y
HY
Vincent Ching
Paul
P
Demay-Drouhard
Hélène C
HC
Bertrand
Clotilde
C
Policar
Leandro C
LC
Tabares
Sun
S
Un
D056831:Coordination Complexes / Q000737:chemistry*; D003545:Cysteine / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D006573:Heterocyclic Compounds, 1-Ring / Q000737:chemistry*; D008301:Maleimides / Q000737:chemistry; D008345:Manganese; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry*; D017433:Protein Structure, Secondary; D013113:Spin Labels
D056831:Coordination Complexes; D006573:Heterocyclic Compounds, 1-Ring; D008301:Maleimides; D010455:Peptides; D013113:Spin Labels; C071349:1,4,7,10-tetraazacyclododecane- 1,4,7,10-tetraacetic acid; C011083:polyproline; C043592:maleimide; D008345:Manganese; D003545:Cysteine