High sensitivity enables reliable sizing of proteins

Size measurement of proteins and other small, poorly scattering molecules in solution has always required a dedicated and specialised optical set-up, or a powerful laser light source that adds to the complexity of the measurement and to the cost. However, the recently launched HPPS (High Performance Particle Sizer) from UK-based Malvern Instruments is said to be highly effective for this category of materials

The sensitivity of the HPPS for protein measurement can be demonstrated using lysozyme, which has a molecular weight of 14,400. When a 0.1mg/ml solution of the enzyme (dissolved in sodium acetate) was subjected to a 5-minute measurement, the monomer diameter of 4nm was measured with a high degree of accuracy. Aggregates, which are difficult to avoid in such small and dilute samples were also measurable, despite comprising less than 0.1% of the total sample volume.

The HPPS incorporates Malvern's patented Non Invasive Back Scatter (NIBS) optics technology, which maximises the detection of scattered light while maintaining signal quality to provide the sensitivity required for measuring molecules smaller than 1000Da.