Mobius instrument measures precise protein charges

Protein molecules carry charges that are influenced by their environment, amino acid sequence, ionic strength and the aqueous solvent pH in which they are dissolved.

The net charge carried by protein molecules is of significant scientific interest since it affects the behaviour of the molecules.

As the ionic strength of the solution increases, for example, more counter ions are present in the vicinity of the protein molecules and the mobility generally decreases due to the electrophoretic effect.

However, measuring protein charge has been a challenging task for conventional phase analysis light scattering (PALS) instruments that can only provide measurements at high concentrations and at high voltages.

In addition, undesirable interactions can often occur, such as that between the proteins and the capillary walls, which diminish the reliability of results.

The application note demonstrates how the Mobius overcomes the limitations of traditional PALS methods, eliminates undesirable interactions and facilitates protein charge measurements at low concentrations - all without damaging the protein itself.

The Mobius mobility instrument is capable of carrying out protein net charge measurements with a moderate antibody concentration of 1.0mg/mL, which are not possible with conventional PALS instruments.

The key to successful measurement of a protein's mobility lies in a much-shortened measurement time and the availability of sufficient data to average away molecular diffusion.

The Mobius from Wyatt Technology is said to achieve these goals through massive parallelism of its light scattering detection and extends the measurable molecular size range below 2nm.

A reduced measurement time of less than 60 seconds, in most cases, contributes to good preservation of precious and fragile protein samples.

The instrument also features a temperature-control capability, making it suitable for performing automated temperature studies.