An automatic solution-sample-changing peristaltic device at biological small angle X-ray scattering beamline

Background: Protein structure in solution can be studied by small-angle X-ray scattering techniques at synchrotron radiation facilities. However, the structure of protein is prone to vary as the radiation damage induced by the intense X-ray beam during the experiments. Purpose: This study aims to develop an automatic solution-sample-changing peristaltic device for biological small angle X-ray scattering experiment. Methods: The injection pump PSD/4 of Hamilton is applied to eliminate the radiation damage of protein by minimizing the X-ray irradiation time of unit volume. In addition, automatic sample-changing, retrieving and cleaning was realized by the coordinated control of PSD/4, the alignment control stage and the sample/buffer control stage. Thus the experiment efficiency is improved. Results: The scattering curves and gyration radius of lysozyme under stationary collection mode and peristaltic collection mode were measured by experiments carried out at biological small angle X-ray scattering beamline of Shanghai Synchrotron Radiation Facility (SSRF). And results show that this device can prevent radiation damage of sample efficiently. Conclusion: The designed functionalities have been achieved as expected. (authors)