Neutron protein crystallography: current status and a brighter future.

Area of Science:

• Biophysics
• Structural Biology
• Biochemistry

Background:

• Hydrogen atoms are difficult to visualize in X-ray crystallography.
• Neutron crystallography offers a complementary method for visualizing hydrogen atoms.
• Recent technological advancements have expanded the capabilities of neutron crystallography.

Purpose of the Study:

• To highlight the advantages of neutron crystallography for studying biological structures.
• To demonstrate the impact of recent technological advances on neutron crystallography.
• To showcase the unique insights gained from neutron crystallography compared to X-ray analysis.

Main Methods:

• Utilizing advanced neutron beamlines and deuterium labeling techniques.
• Collecting high-quality neutron diffraction data from protein crystals.
• Achieving near-atomic resolution (1.5-2.5Å) for proteins (50-175 kDa).
• Employing perdeuterated samples, small crystal volumes (0.1 mm³), and cryogenic temperatures (15 K).

Main Results:

• Successful visualization of hydrogen atoms in protein crystal structures.
• Obtained unique insights into hydrogen-bonding, protonation states, and catalytic mechanisms.
• Revealed details of hydration states not accessible through X-ray methods.
• Demonstrated the feasibility of studying larger proteins and smaller crystals.

Conclusions:

• Neutron crystallography provides crucial, complementary information to X-ray crystallography for biological structure determination.
• Technological advancements have significantly enhanced the power and scope of neutron crystallography.
• Future spallation neutron sources will further revolutionize the field, offering substantial performance gains.