Uridine as a new scavenger for synchrotron-based structural biology techniques

Area of Science:

• Structural biology
• Biophysics
• Biochemistry

Background:

• Synchrotron-based X-ray techniques like macromolecular crystallography (MX) and small-angle X-ray scattering (SAXS) are crucial for protein structure determination.
• Intense X-ray beams can cause structural damage to proteins, leading to aggregation and artefacts, compromising data quality and structural integrity.
• Free radical scavengers are additives used in buffer solutions to mitigate X-ray-induced radiation damage.

Purpose of the Study:

• To evaluate uridine as a free radical scavenger for both SAXS and MX experiments.
• To assess the protective properties of uridine against X-ray radiation damage in protein samples.
• To compare the efficacy of uridine with established scavengers.

Main Methods:

• Macromolecular crystallography (MX) and small-angle X-ray scattering (SAXS) experiments were performed on lysozyme at room temperature.
• Uridine was added to the buffer solutions at various concentrations (e.g., 1 mM for MX, 40 mM for SAXS).
• Radiation damage was assessed using critical dose (D1/2) and other figures of merit; scattering profiles were analyzed for SAXS.

Main Results:

• In MX, 1 mM uridine increased the critical dose (D1/2) by approximately 1.7-fold, comparable to ascorbate and sodium nitrate.
• In SAXS, 40 mM uridine demonstrated a protective effect similar to 5% glycerol and superior to DTT and ascorbic acid.
• The protective effect of uridine was found to be concentration-dependent in both experimental setups.

Conclusions:

• Uridine is an effective free radical scavenger for synchrotron-based protein structural studies using MX and SAXS.
• Uridine offers a viable alternative to commonly used scavengers, showing significant protection against X-ray radiation damage.
• The concentration of uridine directly influences its protective efficacy, allowing for optimized experimental conditions.