Easily assembled digital data acquisition system for the analytical ultracentrifuge

A system for the acquisition of digital data from the analytical ultracentrifuge which uses a commercially available data acquisition board, a standard IBM compatible personal computer (PC), and an interface circuit has been developed. The system uses the signal from the standard Beckman scanner. Preliminary analysis and data reduction are performed at the PC within minutes of data acquisition using simple commercially available software, and final data fitting is performed with a mainframe computer. Procedures are described which allow approach to equilibrium to be followed and attainment of equilibrium to be demonstrated. Data density of approximately 200 points per millimeter column height (approximately 500 points per 100 microliters of sample) allows the use of short columns and hence short run times. Only 2 min are required to collect a complete scan, which is recorded in a format suitable for direct analysis by standard spreadsheet software. This allows multiple sequential scans to be quickly recorded at equilibrium and averaged to reduce noise prior to analysis. The combination of characteristics allows molecular weight determinations to be performed relatively quickly with only a few micrograms of protein. The system is inexpensive and easy to assemble given the centrifuge and a PC.