Double‐Arm Lanthanide Tags Deliver Narrow Gd3+–Gd3+ Distance Distributions in Double Electron–Electron Resonance (DEER) Measurements

摘要: Double-arm cyclen-based Gd3+ tags are shown to produce accurate nanometer scale Gd3+-Gd3+ distance measurements in double electron-electron resonance (DEER) experiments by confining the space accessible metal ion. The results show excellent agreement with predictions both for maximum and width of measured distributions. For proteins, can be attached two cysteine residues located positions i i+4, or i+8, an α-helix. In latter case, additional mutation introducing aspartic acid at position i+4 achieves particularly narrow distribution widths. concept is demonstrated mutants T4 lysozyme maltose binding protein. We report narrowest distributions observed date a By limiting contribution tag mobility distances measured, double-arm open new opportunities study conformational landscape proteins solution high sensitivity.