A1 S2: Dynamic Light Scattering

A1: Bring Your Sample

S2 (Session): The Advanced Applications of in plate Dynamic Light Scattering

Dr. Arne Meyer

XtalConcepts GmbH

Dynamic Light Scattering is a widely used method for any kind of small particle size distribution analysis. The main purpose of this method is the determination of particle sizes, respectively the hydrodynamic radius in the sub-microscopic range, i.e. 1 nm to few µm. It is based on the Brownian motion of those particles. Light scattering methods are non-invasive and therefore a great advantage in the field of particle analysis. SpectroLight 610 is a next generation dynamic light scattering device that allows to perform fully automated DLS-measurements in sample droplets smaller than 0.8 µl on 96 well batch crystallization plates covered with paraffin oil [1]. That offers the possibility to reveal sub-microscopic protein responses in situ when admixed with the various buffers from a screen, highly sample efficient and non-invasively. Screening hits can be easily and quickly identified this way. Most clear droplets are by far no screening-hits, where a protein possesses a monodisperse size distribution, long-term stability and overall quality but instead show aggregates in vast size variations. Among those clear droplets, the few “good” buffer conditions can be identified with ease thanks to the sophisticated data plotting options. In-plate DLS also demonstrated its potential for another field of great significance, the identification of protein detergent complexes. Solubilization of partial hydrophobic membrane proteins is a pre-requisite for subsequent crystallization trials and frequently requires a protein specific detergent [2]. Utilization of an unsuited detergent results in easily detectable aggregates. Therefore in-situ DLS offers a standardized way for membrane protein treatment. Moreover, SpectroLight 610 is a fully fledged imaging system with optional UV-light illumination for rapid protein crystal identification based on intrinsic tryptophane fluorescence [3]. In combination with DLS the range of particle detection covers the molecular world to even microscopic objects.

[1] K. Dierks et al. Dynamic light scattering in protein crystallization droplets: Adaptation for analysis and optimization of crystallization processes, Crystal Growth and Design No. 8, p. 1628 (2008).

[2] G.G. Privé, Detergents for the stabilization and crystallization of membrane proteins, ScienceDirect, Methods 41, 388-397 (2007).

[3] K. Dierks, et al. Efficient UV detection of protein crystals enabled by fluorescence excitation at wavelengths longer than 300 nm, Acta Crystallogr. F Struct. Biol. Commun. 66(Pt 4), (2010).