A computer program for the calculation of sedimentation coefficients and molecular weights of nucleic acids

Abstract

A computer program has been developed for the calculation of sedimentation coefficients of macromolecules centrifuged on sucrose gradients in swing-out rotors. The accuracy of the program has been tested with both RNA and DNA. Human ribosomal RNA was centrifuged and the sedimentation coefficients of the two main peaks were calculated to be 28 and 18 S. Randomly sheared DNA was fractionated on a sucrose gradient and the computed molecular weights of the fractions corresponded very closely with their sizes as estimated by agarose gel electrophoresis. This not only verifies the calculation of s 20,w but independently confirms Studier's equation relating s 20,w to molecular weight of DNA. The program is written in BASIC and can handle any swing-out rotor for which the distance from the center of rotation to the tube bottom and the internal tube radius is known.