Pink-Beam Serial Synchrotron Crystallography at Pohang Light Source II

Abstract

Serial crystallography (SX) enables the determination of room-temperature structures with minimal radiation damage. The photon flux of the pink beam of 1.2% bandwidth (BW) is one order higher than that of the monochromatic beam from a silicon crystal monochromator, and the energy resolution of 1.2% BW is enough to solve the structure; therefore, it is useful to use the pink beam for time-resolved serial synchrotron crystallography (SSX). Here, we demonstrate a pink-beam serial synchrotron crystallographic study at the 1C beamline at the Pohang Light Source II. Lysozyme crystals embedded in a beef tallow injection matrix were delivered through a syringe into the X-ray interaction point. Pink-beam SSX was performed with different X-ray exposure positions to the injection stream (center and edge) and X-ray exposure times (50 and 100 ms). All lysozyme crystal structures were successfully determined at a high resolution of 1.7 Å. Background analysis showed that X-ray diffraction data exposed to the edge of the injection stream could improve the signal-to-noise ratio. All the diffraction data and room-temperature lysozyme structures were comprehensively compared. The data collection strategy and analysis will be helpful in further pink-beam SSX experiments and their applications.