Technology Opportunities

Fills the gap between crystallography and optical imaging

Highlights

• Information about macromolecules is encoded in their shape and the way they are assembled.
• Most self-assembled structures cannot be crystallized and investigating these systems relies on analysing X-ray scattering in the solution.
• The structure of crystals can be established using X-ray crystallography software, but in solution, the X-ray scatterers are found in all possible spatial orientations and this significantly reduces the amount of structural information from three-dimensional to one-dimensional.
• There is thus a need for different approaches when performing measurements and when analysing data to solve the structure of macromolecules.

Our Innovation

Software program, X+, analyses X-ray scattering from macromolecules in solution. Thoroughly analyses both structure and form factors to model the entire scattering signal, allowing extraction of relevant physical parameters including electron-density distribution, correlation distances, domain sizes, elastic constants and parameters describing intermolecular interactions.

Figure: Radially integrated measured scattering intensity from 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) at room temperature (open circles), fitted with a model containing both form and structure factors (solid line). The form factor model (dashed line) is of infinite flat multilayer with Gaussian electron density profiles along the z-axis (normal to the plan), with the following parameters. (i) A Gaussian layer with an electron density amplitude of 210 e 〖nm〗^(-3), FWHM of 0.317 nm and centred at the origin, to represent the lipid tails. (ii) Two more Gaussian layers, centred at 1.39 nm and -1.39 nm, with FWHM of 0.632 nm and electron density amplitude of 445 e 〖nm〗^(-3), to represent the head groups (see inset). The modified Caille theory structure factor (Zhang et al., 1994) was used with the following parameters. Lamellar repeat distance, d, of 5.8 nm, domain size of ca. 30 layers, with a standard deviation of ca. 15 layers and the Caille parameter, η=(πh^2 k_B T)/(2d^2 √KB)=0.11, where h=qd/2π, K is the modulus for layer curvature and B is the bulk modulus for layer compression. To reconstruct the signal, a background function, B(q)=0.00019 q^2.66 was used (dotted line).

Key Features

• X+ provides a means to easily study and thoroughly analyse many important biological self-assembled structures and soft-matter supramolecular structures.
• Can be used to investigate non-crystalline self-assembled structures with features spanning length scales in the range 0.1– 100 nm.
• Enables the analysis of solution X-ray scattering from self-assembled systems, including liquid crystals (both lyo- and thermotropic), self-assembled polymers, various supramolecular complexes and particularly biomolecular assemblies.

Development Milestones

• Seeking funding for ongoing development and industrial cooperation

The Opportunity

System may be used for analysing all types of large molecular structures in solution, such as:

• Viruses
• Microtubules
• Nanostructures
• Membranes
• Liquid crystals
• Polymer assemblies