Synchrotron Powder Diffraction Study of Radiation Damage in Langmuir Blodgett Nanotemplate Crystallised Protein

Jonathan P Wright,Claudio Nicolini,Eugenia Pechkova

doi:10.3844/ajbbsp.2014.162.168

Abstract

Polycrystalline samples of lysozyme were prepared with and without a Langmuir-Blodgett (LB) thin film template via both the hanging drop method and batch crystallisation. Powder diffraction methods are used to compare these samples and to measure their resistance to radiation damage at room temperature. The X-ray induced amorphisation of the samples was followed as a function of time and it was shown that diffraction does not entirely disappear even at very long exposure times. Two distinct kinetic timescales are evident suggesting that early and late stage processes are quite different. Radiation damage was also shown to be localized in the sample in the region where the beam impinges.

Highlights

Protein crystallization is the key bottleneck in the structure determination pipeline
By using conventional drop crystallisation the crystals were too large for powder diffraction
For powder diffraction experiments it was important to use the batch crystallization method in order to produce a large number of very small crystallites

Summary

Introduction

Protein crystallization is the key bottleneck in the structure determination pipeline. New methods to produce crystalline proteins are needed. Previous experiments on templated crystals (Pechkova et al, 2009; 2010; Belmonte et al, 2012) have shown that the LB nanotemplated crystals show improved diffraction quality and greater resistance to radiation damage. The advent of powder diffraction methods which can be applied to protein samples (Von Dreele, 1999; Margiolaki and Wright, 2008) gives a new tool to examine crystalline quality. Powder methods measure data from millions of crystallites and so they are not so sensitive to outliers and instead give the bulk properties of a sample. The diffraction quality and resistance to radiation damage of different samples are compared using the powder diffraction method. We will show that radiation damage processes during the early stages of exposure to the X-ray beam are quite different to those at longer exposure time

Methods

Results

Conclusion