Data Analysis Of Small Angle X-Ray Solution Scattering And Its Application To Human Tumour Necrosis Factor

Abstract

Small Angle X-ray Scattering analysis was used for the study of the protein, Human Tumour Necrosis Factor (TNF) homogeneously dispersed in solution. The experiment consisted in sending a well collimated beam of synchrotron radiation of wavelength, λ through the sample and measuring the variation of the intensity as a function of the scattering angle θ through the scattering vector s = 2sinθ /λ. The scattering curve recorded at very low angles was first extrapolated to the origin, joined to data recorded at so called wide-angles and extrapolated to infinity to obtain a complete scattering curve for the analysis using computation subroutines that can run iteratively. The complete scattering curve was then used to extract the size, shape and the organisation of the macromolecules in solution. The results obtained reveals that in solution, the TNF is a trimer with a radius of gyration of 25.5±0.3 Ă and a maximum diameter of at least 84 Ă.

KEY WORDS: Small Angle X-Ray Scattering, Tumour Necrosis Factor, Radius of Gyration, Maximum Diameter.

Global Journal of Pure and Applied Sciences Vol.11(1) 2005: 141-148