Characterization and Total Recovery of the Component Proteins of a Deoxyribonucleoprotein

Abstract

RECENT developments suggest that the normal nuclei of all somatic cells of an organism contain the same quantity¹ and kind² of deoxyribonucleic acid, but that the different cell types within the organism may differ³ in regard to the proteins associated with deoxyribonucleic acid: deoxyribonucleic acid appears to be specific for species and the associated proteins specific for cell type. The deoxyribonucleic acid of a species has been shown⁴ to be multiple with regard to nucleo-base ratios and may consist of as many chemical individuals as there are genes, while at the same time among different species the deoxyribonucleic acid-associated proteins of similar organs may be similar. Classical genetics postulates that each cell type is, through its chromosomes, endowed with all the potentialities of the species, but expresses only those potentialities which make up its own specific character. If the deoxyribonucleic acids are the physical correlate of the genetic potentialities, the implication arises that cellular differentiation may be mediated through attachment of cell-specific proteins (histones, etc.) to species-specific deoxyribonucleic acids. Indeed, the hypothesis that the former function as gene conditioners was advanced by Stedman⁵ long before the emergence of chemical proof for the multiplicity of de-oxyribonucleic acid, and has been reasserted⁶ on the basis of experimental evidence for the cell-type specificity of certain preparations of deoxyribonucleic acid-associated proteins.