Density Gradient Centrifugation of Human and Bovine Parathyroid Hormone

Abstract

The high speed of recent model preparative ultracentrifuges, developing over 400,000 g, has made it possible to apply the sucrose gradient method to determine the sedimentation constant of peptides with molecular weights below 10,000. Using this technique the sedimentation constants of bovine and human parathyroid hormone were determined. The bovine peptide was compared with lysozyme and corticotropin; S20,w relative to lysozyme was found to be 1.08 at pH 4.7 and 1.23 at pta 9.5. A sensitive radioimmunoassay was employed to measure the distribution of limited quantities of human parathyroid hormone; the human hormone showed a sedimentation constant of 1.09, virtually identical with that of the bovine hormone, suggesting that they may be quite similar in size.