The application of intensity fluctuation spectroscopy to molecular biology.

Abstract

In the ten years since Cummins, Knable & Yeh (1) used light-beating spectroscopy to measure the Doppler shift of light scattered from a flowing fluid, and Pecora (2) developed a theoretical basis for interpreting the spectrum of scattered light in terms of the dynamics of the scatterers, the subject has undergone enormous growth. While the technique is still often called light-beating spectroscopy, it is generally agreed that better names are intensity fluctuation spectroscopy or photon correlation spectroscopy. New and improved theories and experimental techniques have increased the precision of the method and broadened the scope of chemical, physical, and biological problems to which it can be applied. Intensity fluctuation spectro­ scopy, like other forms of spectroscopy, can be used to study molecular dynamics in vitro and in vivo. It is this feature that makes it particularly useful to molecular biology. This review covers all the material published since the previous review of Pecora (3) through mid-1974. Particular attention is paid to the specific application of intensity fluctuation spectroscopy to molecular biology and to new theoretical and experimental developments that have led to improvements in both scope of applicability and precision. In addition to the review by Pecora (3), various aspects of the subject have been reviewed by Ford (4), Ford et al (5), Pike & lakeman (6), and Cummins (7). In order to make the material readily comprehensible to molecular biologists, I have included in the introduction a summary of basic concepts and theories without detailed derivations and without citing the original sources. The interested reader is referred to the reviews mentioned above and to Cummins & Swinney (8), Cummins & Pike (9), and Champeney (10) for a thorough treatmen t. Similarly, in the sections on specific topics, previously well-established results are simply stated without citing the original sources, whereas recent extensions or new results are given with reference citations.