Small acidic peptides from wheat germ chromatin. I. Isolation and biochemical characterization

RNA synthesis in cell and cell-free systems is inhibited by a family of acidic, low molecular weight chromatin peptides (CPs). These peptides were extracted from deproteinized DNA of prokaryotic and eukaryotic cells, but the low yield of purified material by this procedure hinders efforts aimed at understanding their action mechanism in gene regulation. In this report we describe two purification methods of CPs from an easily available source, wheat germ. A comparison is made between the method starting from deproteinized DNA and the method from purified chromatin. The biological effects (inhibition of L1210 cell growth and DNA in vitro transcription) of CPs from wheat germ together with their chemical characteristics (molecular weight, amino acid composition and presence of phosphoserine) show strong homology with those of CPs from other sources. These results suggest a possible role of these chromatin peptides in controlling gene expression.