EXPERIMENTAL SETUPS

PROTEIN CHRYSTALLOGRAPHY (PX)

Project Description

Protein Crystallography (PX) is a technique used to study biological molecules such as proteins, viruses and nucleic acids (RNA and DNA) to a resolution higher than ~5 Å. The present project consisted of the design, procurement and commission of a complete experimental setup for PX:

• Slits box -prepares the X-Ray beam.
• Sample diffractometer -holds and turns the sample during the experiment.
• CryoSystem -keeps the sample in cryogenic conditions.
• Beam stopper -protects the CCD camera from the direct beam.
• High resolution sample positioning camera -provides information for the sample centering.
• CCD camera -collects the beam diffraction for the sample.
• Main support -supports all the elements in very precise relative positions.
• Support and alignment table -aligns the complete setup with the beam.

Engineering Skills

• Mechanical design and integration,
• Precision mechanics,
• Vacuum technology,
• Production and control of the digital mock-up, as well as the set of manufacturing drawings,
• Manufacturing follow up.

Key Points

Integration of several high precision commercial devices with customised devices in a complete high performance experimental setup.
The slits box is a vacuum chamber, which houses the devices shown in Figure 3.. A flexible design of the Slits Box allows different configurations of its elements, for optimization issues.

The beam stopper is a small lead cylinder placed in front of the CCD and very close to the sample. It must be removed from its working position during sample exchange operation. An automatized protocol for such operation has dramatically reduced this non-productive time. A tightly tolerated high-stiffness precision support made in aluminum is the key structural element for this experimental setup since it provides high-precision constraints for the relative positions of all the components.

Main performances

• Beam size of 100 μm,
• Self-alignment system and semiautomatic sample centring,
• 2 axis automatic beam stopper system, 10 μm precision,
• 2-axis position and focus system for CCD camera