Methods for increasing the sensitivity of sedimentation velocity analysis: a signal averaging Rayleigh optical system for the Beckman Instruments Optima XL-A analytical ultracentrifuge

摘要

A large increase in the sensitivity of sedimentation velocity experiments can be achieved by combining time derivative analysis with signal averaging. Computation of the time derivative results in the complete elimination of time independent optical background. The ability to rapidly acquire sedimentation profiles using real-time Rayleigh interferometry has made it possible to average large numbers of profiles over relatively short periods of time. Currently available, inexpensive computers and video frame grabbers have made it possible to acquire and reduce Rayleigh interferograms at the rate of about 1 per second. The ability to achieve high sensitivity means that high affinity interacting systems that can not be studied by the conventional ultracentrifugal methods are now accessible to analysis by analytical ultracentrifugation. A Rayleigh optical system for the Beckman Instruments Optima Series XL-A Analytical Ultracentrifuge is described, and methods of data acquisition and reduction are presented.