Question

Difference between monodisperse and polydisperse

Answer 1

Polydispersity is representative of the protein particle size distribution width. If the DLS data analysis assumes a Gaussian distribution of particles, given as a single peak, polydispersity of the sample is the peak width at half its height. Percent polydispersity can be calculated by dividing polydispersity by mean hydrodynamic radius (RH) and expressing it as a percentage. A protein sample with less than 20% polydispersity is regarded as monodisperse. As detailed in Experimental design, having a monodisperse protein sample is often a good indicator of crystallization propensity. The x axis is indicative of the protein hydrodynamic radius in nanometers. The y axis represents the percentage intensity of scattered light. % Pd, percent polydispersity. Adapted with permission from Malvern Instruments, Ltd.