Monthly Newsletter

Wyatt Technology Corporation, the world leader in absolute macromolecular characterization instrumentation and software, announced today that the Université de Provence and Université de la Méditerranée in Marseille, France, have implemented the innovative Wyatt Multi-Angle Light Scattering (MALS) detectors for use in their Biological Macromolecules Joint Research Unit. The instruments are used for the characterization of transmembrane proteins, determining their quaternary structure and following their retention during protein handling. Transmembrane protein characterization is of increasing importance for the pharmaceutical industry as these proteins are key determinants of the pharmacokinetics of drugs. Wyatt's MALS detectors offer an easy-to-use, efficient alternative to traditional laborious in vitro characterization techniques.

Transmembrane proteins are key components of living cells, constituting one third of the Open Reading Frames (ORFs) of virtually all genomes. They perform a wide range of functions, including translation of extracellular signals to intracellular responses, ion transport and nutrient transport. Transmembrane proteins are targeted by the vast majority of drugs as they play key roles in diabetes, hypertension, depression, arthritis, cancer and many other diseases.

When present in their native environment, transmembrane proteins are inserted via hydrophobic segments in a lipidic bilayer. Conventional in vitro characterization of transmembrane proteins requires the extraction of the proteins from the membrane and subsequent maintenance in a soluble and native state. This is generally achieved using amphiphilic compounds, termed detergents, yielding protein-detergent complexes (pdc). However, several transmembrane proteins are naturally found as oligomers and maintaining this precise macromolecular assembly is a crucial issue for further studies. In addition, classical SEC column calibration does not apply in the case of pdc, whose volume and shape depends on the detergent fraction.

For this particular application, Wyatt's MALS instruments were used to perform a quaternary structure study of the Methanosarcina mazei CorA transporter in two detergents. MALS technology was used in conjunction with refractometry and UV280nm absorbance. This combined solution was able to solve a "two equations with two unknown parameters" system, providing masses of protein and detergent in each pdc. This approach provided hints about the retention of the native, and thus active, membrane protein quaternary structure, which is a crucial issue for crystallization or other biochemical studies, without performing laborious activity tests.

Experimental results prove that Wyatt's MALS instrumentation surpasses traditional in vitro characterization techniques, providing a straightforward method capable of accurate, reliable characterization of transmembrane proteins. The unparalleled capabilities of Wyatt's MALS detectors for characterizing transmembrane proteins are illustrated in a new application note, entitled "Membrane Protein Quaternary Structure Analysis and Detergent Selection", which is available to download from www.wyatt.com