Nucleoproteins and Gene Structure *

It is generally recognized that the genes or inheritable characters of all organisms, with the possible exception of the bacteria, are localized in the cell nucleus, and, more specifically, in the chromosomes. The intrinsic relationship between the genes and the chromosomal nucleoproteins is supported by cytochemical as well as by photochemical evidence: Desoxyribonucleoproteins represent the quantitatively most important constituents of the chromosomes, the spacing between the nucleotide-rich regions of the giant salivary chromosomes is identical with that between the individual genes, and the wave-length of ultraviolet radiation which is most effective in producing mutations is the one most strongly absorbed by the pyrimidine and purine nuclei of the nucleic acid moiety of the molecule. The assumption that genes are nucleoprotein molecules would thus appear to have a high degree of probability (cf. ref. 26). If we wish to interpret genetic phenomena in terms of nucleoprotein chemistry, quantitative information on the size, shape, and detailed fine structure of these conjugated protein molecules is an essential prerequisite. Since the fall of 1944, a group at this Institute, including Dr. S. C. Shen, P. Macaluso, S. Davis, R. Beloff, M. Friedman, J. Wagman, G. Goldstein, D. Suchoff, and J. Schryver, in collaboration with the writer, has been studying representative desoxyribonucleoproteins with the aid of physical-chemical methods heretofore applied to globular and fibrous proteins, as well as to synthotic high-polymers. They include measurements of molecular sedimentation, diffusion, electrophoresis, viscosity, flow-birefringence, ultraviolet absorption, as well as the usual chemical analyses. X-ray diffraction and electron-optical studies are projected. In parallel to the experimental part of this work, a theory of gene structure is being developed. The present report deals with both aspects of the problem.