Direct measurement of histone peptide elongation rate in cleaving sea urchin embryos.

Regulation of protein synthesis can be exercised at a number of levels. One of the more experimentally difficult levels to approach has been the measurement of peptide elongation rate. This paper presents a new application of the cyanogen bromide (CNBr) cleavage of proteins in a direct measurement of histone peptide elongation rate in cleaving sea urchin embryos (Strongylocentrotus purpuratus). The data indicate an elongation rate (at 15 degrees C) for histones H2B and H1 alpha of 0.69 and 0.80 codons per s, respectively. These values fall within the range of previously published values of average peptide elongation rate for total protein in these cells. This method should be generally applicable to many systems for which the measurement of peptide elongation rate may provide a key to the understanding of the regulation of protein synthesis.