Trichromatic Concept at SPring-8 RIKEN Beamline I

Area of Science:

• Structural Biology
• X-ray Crystallography
• Biophysics

Background:

• The Institute of Physical and Chemical Research (RIKEN) developed SPring-8 RIKEN beamline I for advanced structural biology.
• The beamline supports both protein crystallography and small-angle X-ray scattering experiments.
• Synchrotron radiation enables advanced techniques like multiple-wavelength anomalous-dispersion (MAD) phasing.

Purpose of the Study:

• To design and implement a beamline optimized for MAD phasing in protein crystallography.
• To minimize systematic errors in anomalous diffraction measurements for MAD.
• To enable quasi-simultaneous data collection at multiple wavelengths.

Main Methods:

• Development of a 'trichromatic concept' for simultaneous data acquisition at three wavelengths.
• Utilizing dichromatic synchrotron radiation from coaxial undulators with vertical polarization.
• Employing a transparent diamond crystal to branch the X-ray beams.

Main Results:

• The protein crystallography branch was designed based on the trichromatic concept.
• Initial commissioning successfully produced three distinct monochromated undulator beams.
• The beams were verified at the trichromator's endpoint.

Conclusions:

• RIKEN beamline I is optimized for precise MAD data collection in protein crystallography.
• The trichromatic concept minimizes systematic errors, improving phasing accuracy.
• The beamline is ready for advanced structural biology research requiring accurate MAD phasing.