[Histones from Trypanosoma lewisi nuclei]

Abstract

A preparation of total histones has been isolated for the first time from the purified fractions of T. lewisi cell nuclei and characterized in terms of its chemical composition and RNA-polymerase activity. A special attention during the isolation procedure was given to the repression of proteolytic degradation of the histones. The amount of protein in the chromatin is equivalent to that of DNA. The amino acid composition and heterogeneity of the protein during polyacrylamide gel electrophoresis in an acid system and in the presence of sodium dodecyl sulfate are typical for histones. Using two-dimensional electrophoresis, differential staining of electrophoregrams and ion-exchange chromatography on CM-cellulose the total preparation has been found to be made up of five fractions: two -- arginine-rich (one of them identical to histone H4, the other being similar to histone H3 from calf thymus); two -- moderately lysine-rich fractions, slightly differing in their properties from histones H2A and H2B from calf thymus, and one specific fraction with mol. weight of 16 000 and an extremely high positive charge. The above methods in combination with specific extraction have been used to demonstrate the absence of a typical lysine histone in the preparation, which is correlated with the absence of typical methaphase chromosomes during mitosis in T. lewisi.