iBIXで飛行時間法により収集されたタンパク質中性子回折データに対するプロファイルフィッティング法の適用

抄録

Single crystal neutron diffractometer is a powerful tool for elucidating the hydrogen and proton structures of biological macromolecules. We developed and employed a profile fitting method for the peak integration of neutron time-of-flight diffraction data collected by the IBARAKI Biological Crystal Diffractometer (iBIX) at the Japan Proton Accelerator Research Complex (J-PARC) for ribonuclease A single crystal. In order to determine proper fitting functions, four asymmetric functions were evaluated using strong intensity peaks. A Gaussian convolved with two back-to-back exponentials was selected as the most suitable fitting function, and a profile fitting algorithm for the integration method was developed. The intensity and structure refinement data statistics of the profile fitting method were compared to those of the summation integration method. It was demonstrated that the profile fitting method provides more accurate integrated intensities and model structures than the summation integration method at higher resolution shells. The integration component with the profile fitting method has already been implemented in the iBIX data processing software STARGazer and its user manual has been prepared.