Small Angle X-ray Scattering Rob Lewis Centre for X-ray Physics and Imaging School of Physics and Materials Engineering Monash University

Bragg’s Law  d 2d sin θ = nλ or d = nλ/2sin θ Small angles (< 5o ) give information on large structures – 1 to 100nm d 

SAXS Crystallography Microstructure Structure 10-11m 10-9 10-7 10-5 Elliot Gilbert ANSTO

Diffraction Configuration

SAXS Works on live wet specimens Time resolution - sub microsecond Two main variants Solution scattering Protein folding Protein ligand interactons Fibre diffraction Tissue analysis Muscle operation

Diffraction

Diffraction

6 models of sAPPα695 Dark indicates areas of superposition A B and C are orthogonal views Crystal model of N terminal domain of APP Gralle et al Biophys J 83, 3513 (2002)

Collagen Axial Structure Tropocollagen Secreted from cell 1.5nm N Overlap Gap 67nm Overlap Gap Overlap Gap Proteolytic cleavage Procollagen N protease Procollagen C protease 10.4nm 300nm Cross links involve lysyl oxidase C

Collagen Rat tail tendon Camera length: 9.35m Wavelength: 0.154nm

Different tissues

Diffracted Intensity: Trend

Osteochondral Autograft Transplantation OATS

OATS surgical technique MARIARC MRI, University Liverpool, UK Incorrect graft harvest and recipient socket angles, are the most common OAT surgical errors and reasons for failure.

Slide: S Arnotzky

Lamb Cartilage Study

Myelin Diffraction

Muscle diffraction Resting Contracted shows two diffraction patterns taken form a live muscle. One whilst resting and the other at the peak of contraction. The intensity of SR allows real movies to be taken at a molecular level of muscle as it contracts and is yielding great insight into how mucle really works OK now to more familiar territory. Imaging