Digitization of sedimentation equilibrium and velocity data for analysis by minicomputer
Holzman, T.F.; Leytus, S.P.; Baldwin, T.O.; Mangel, W.F.
Analytical Biochemistry 119(1): 62-72
ISSN/ISBN: 0003-2697 PMID: 7041695 DOI: 10.1016/0003-2697(82)90665-0
A fast, efficient and accurate method for obtaining solute sedimentation coefficients and MW from analytical ultracentrifugation data is described. Recorder tracings from the photoelectric scanner of a Beckman Model E analytical ultracentrifuge are analyzed with a computer program after being entered into a minicomputer via a digitizer board. The method is a simple, low-cost and resource-efficient alternative to complex methods of modifying the ultracentrifuge for similar purposes. Even nonideal and polydisperse solute samples may be analyzed. To illustrate this method sedimentation equilibrium data for a mutant bacterial luciferase, AK-6, are analyzed. Two major species are detected, the dimeric enzyme with an apparent mass average MW, .hivin.Mw,app, of 71,000 and dissociated subunits with an .hivin.Mw,app of 40,000. This method is used to calculate the sedimentation coefficients of native and proteolyzed samples of bacterial luciferase from 3 spp. of luminous marine bacteria [Vibrio harveyi, Vibrio fischeri and Photobacterium phosphoreum].