What is a bead model?

Array of beads

A bead model within the context of this web presentation is a multisphere representation of a single protein or a protein complex. The arrangement of these spheres (or beads) is governed by a set of rules that allows such models to be interpreted in terms of their hydrodynamic or solution scattering parameters. These parameters include M, V, Rg, the translational and rotational, frictional coefficients, the diffusion coefficients (Dt and Dr), the rotational relaxation times and their harmonic mean, and the intrinsic viscosity.

Bead models that are used in the calculation of hydrodynamic parameters are commonly referred to as hydrodynamic bead models, whereas bead models that are used in the calculation of solution scattering parameters are known as Debye sphere models. While rules used for generating hydrodynamic and debye sphere models can be different, it is not uncommon to use a single model to predict both hydrodynamic and scattering properties. The benefit of being able to derive both properties can be offset by the reduced accuracy of those calculated parameters.