Advanced Anisotropy Concepts

Abstract

In the preceding two chapters we described steady-state and time-resolved anisotropy measurements, and presented a number of biochemical examples that illustrate the types of information available from these measurements. Throughout these chapters we stated that anisotropy decay depends on the size and shape of the rotating species. However, the theory that relates the form of anisotropy decay to the shape of the molecule is complex, and was not described in detail. In the present chapter we provide an overview of the rotational properties of non-spherical molecules, as well as representative examples. For the initial topic in this chapter we describe associated anisotropy decays. Such decays occur when the solution contains more than one type of fluorophore, or the same fluorophore in different environments. Such systems can result in complex anisotropy decays, even if the individual species each display a single-exponential anisotropy decay.